基于量子蒙特卡罗的地震波反演方法

The primary approaches for people to understand the inner properties of the earth and the distribution of the mineral resources are mainly coming from surface geology survey and geophysical/geochemical data inversion and interpretation. The purpose of seismic inversion is to extract information of the subsurface stratum geometrical structures and the distribution of material properties from seismic wave which is used for resource prospecting, exploitation and the study for inner structure of the earth and its dynamic process. Although the study of seismic parameter inversion has achieved a lot since 1950s, some problems are still persisting when applying in real data due to their nonlinearity and ill-posedness. Most inversion methods we use to invert geophysical parameters are based on iterative inversion which depends largely on the initial model and constraint conditions. It would be difficult to obtain a believable result when taking into consideration different factors such as environmental and equipment noise that exist in seismic wave excitation, propagation and acquisition. The seismic inversion based on real data is a typical nonlinear problem, which means most of their objective functions are multi-minimum. It makes them formidable to be solved using commonly used methods such as general-linearization and quasi-linearization inversion because of local convergence. Global nonlinear search methods which do not rely heavily on the initial model seem more promising, but the amount of computation required for real data process is unacceptable. In order to solve those problems mentioned above, this paper addresses a kind of global nonlinear inversion method which brings Quantum Monte Carlo (QMC) method into geophysical inverse problems. QMC has been used as an effective numerical method to study quantum many-body system which is often governed by Schrödinger equation. This method can be categorized into zero temperature method and finite temperature method. This paper is subdivided into four parts. In the first one, we briefly review the theory of QMC method and find out the connections with geophysical nonlinear inversion, and then give the flow chart of the algorithm. In the second part, we apply four QMC inverse methods in 1D wave equation impedance inversion and generally compare their results with convergence rate and accuracy. The feasibility, stability, and anti-noise capacity of the algorithms are also discussed within this chapter. Numerical results demonstrate that it is possible to solve geophysical nonlinear inversion and other nonlinear optimization problems by means of QMC method. They are also showing that Green’s function Monte Carlo (GFMC) and diffusion Monte Carlo (DMC) are more applicable than Path Integral Monte Carlo (PIMC) and Variational Monte Carlo (VMC) in real data. The third part provides the parallel version of serial QMC algorithms which are applied in a 2D acoustic velocity inversion and real seismic data processing and further discusses these algorithms’ globality and anti-noise capacity. The inverted results show the robustness of these algorithms which make them feasible to be used in 2D inversion and real data processing. The parallel inversion algorithms in this chapter are also applicable in other optimization. Finally, some useful conclusions are obtained in the last section. The analysis and comparison of the results indicate that it is successful to bring QMC into geophysical inversion. QMC is a kind of nonlinear inversion method which guarantees stability, efficiency and anti-noise. The most appealing property is that it does not rely heavily on the initial model and can be suited to nonlinear and multi-minimum geophysical inverse problems. This method can also be used in other filed regarding nonlinear optimization.

有源电磁扩散场克希霍夫积分偏移

As active electromagnetic method, field data of CSAMT method follow the equation of diffusion. Propagting in solid earth media, diffusion EM signal has strong attenuation and dispersion, otherwise seismic wave shows weak attenuation and dispersion, therefore the resolution power of CSAMT method is not better than seismic reflection method. However, there is consistence and similarity between EM signal and seismic wave in wave equation, we can apply Kirchhoff integral migration technique, a proven one in seismic method in time domain, to carry out seduo-seismic processing for CSAMT signal in frequency domain so that the attenuation and dispersion could be made compensated in some extent, and the resolution power and interpretation precision of active EM wave could be improved. Satisfying passive homogeneous Helmholtz quation, we proceed with Green theorem and combine the active inhomogenous Helmholtz quation, the Kirchhoff integral formula could be derived. Given practical problems, if we only consider the surface integral value, and assume that the intergral value in other interface is zero, combined with Green theorem in uniform half space, the expression could be simplified, and we can obtain frequency-domain Kirchhoff integral formula in surface, which is also called downward continuation of EM field in frequency domain. With image conditions and energy compensation considered, in order to get image conditions in time domain Fourier inverse transformation in frequency domain can be performed, so we can formulate the active Kirchhoff integral migration expression. At first, we construct relative stratified model, with different frequency series taken into account, then we change the distances between transmitter and reciever, the EM response can be obtained. Analyzing the EM properties, we can clarify near and far zone that can instruct us to carry out transmitter layout in practical application. Combined with field data surveyed in far zone, We perform Kirchhoff integral migration and compare the results with model to interpret. Secondly, with far field EM data, we apply TM mode to get EM response of given 2D model, then apply Kirchhoff integral migration on modelling data and interpret the results.

非自喷层测试及评价解释技术研究与应用

Now low porosity and low permeability reservoir is one of the main targets of exploration for the onshore oilfields of China. Most of the reservoirs are none flowing because of bad formation percolation condition, poor gas oil ratio , low formation pressure coefficient and other factors. In the recent years, a number of domestic oilfields have carried out some research work and achieved some success on oil testing and production technology in such formation. But by now, there is still no systematic and mature technology, particularly testing technology in none flowing formation is still needed further study. Based on study the key problem of well testing and interpretation technology in none flowing formation, solve the important problems in well testing technology, continuously improve and innovate geological information acquisition technology for none flowing reservoir, accurately acquire boundary information and evaluate reservoir flow characteristics. Its wide application remarkable result has shown. The main results and cognitions obtained from research are as follows: 1. This new technology research results help solve the occurrent problems in well testing process for none flowing formations, such as small investigation radius, poor representative of interpretation results from the poor data, low level application of interpretation results. This new technology helps create favorable conditions for early precise reservoir evaluation and reduction of the risk of exploration. 2. The technological difficulties for none flowing well testing are successfully solved by using none flowing formation combined mechanical tool string .This method has been proved by its applications to be able to improve the efficiency of the testing and the quantity of the acquired test data ,and so as to enhance the application of the interpretation results of the test in development of oil fields. 3. The application of the rotary formation tester, selective test valve, well testing string and their allier tools help to resolve problems such as the operation of opening and shutting-in the well under different well conditions, to broaden the scope of well test technology for none flowing formations. 4. Refined Testing Technique for production Wells has greatly shortened the testing dwration and improved the efficiency and accuracy of operation, enriched test results, and at the same time created conditions for conducting multi-well interference well testing.

青藏高原东部长周期大地电磁测深研究

As a complement to conventional MT, Long-period Magnetotellurics (LMT) has been developed at low frequency for soundings of deep electric structures. Eastern Himalayan Syntaxis (EHS) and surrounding area is a key place for the study of dynamics of the uplift of Tibetan plateau. Experiments in the pioneer studies for EHS3D project showed that the study area shares an unusual low resistive crust and upper mantle. Conventional MT could not provide sufficient information about the deep structures of the study area that requested long period MT measurement to be complemented. This thesis presents the LMT studies in eastern Tibet along the EHS3D-3 Profile from Xiachayu to Yushu including data acquisition, processing, inversion and interpretation. The effective period of the measured LMT signals extend from 10s up to 30000s for the duration more than one week measurement. The resulting model shows that the LMT sounding coincides with the MT data in overlapped periods. Especially the induction arrows and tippers derived from LMT data provide more information about the base of the conductors beneath the plateau with higher resolution. Anomalous induction coefficients and 2-D model suggest extensive conductive bodies beneath Lhasa block and Qiangtang terrain which would be a possible evidence for partial melt and fluids at depth.

复杂地质条件下高精度地震勘探技术研究与应用-以泌阳凹陷为例

In order to carry out high-precision three-dimensional "integration" for the characteristics of the secondary seismic exploration for Biyang Depression, in the implementation process, through a combination of scientific research and production, summed up high-precision seismic acquisition, processing and interpretation technologies suitable for the eastern part of the old liberated areas, achieved the following results: 1. high-precision complex three-dimensional seismic exploration technology series suitable for shallow depression Biyang block group. To highlight the shallow seismic signal, apply goal-based observing system design, trail from the small panel to receive and protect the shallow treatment of a range of technologies; to explain the use of three-dimensional visualization and coherent combination of full-body three-dimensional fine interpretation identification of the 50-100 m below the unconformity surface and its formation of about 10 meters of the distribution of small faults and improve the small block and stratigraphic unconformity traps recognition. 2. high-precision series of three-dimensional seismic exploration technology suitable for deep depression Biyang low signal to noise ratio of information. Binding model using forward and lighting technology, wide-angle observation system covering the design, multiple suppression and raise the energy of deep seismic reflection processing and interpretation of detailed, comprehensive reservoir description, such as research and technology, identified a number of different types of traps. 3. high-precision seismic exploration technology series for the southern Biyang Depression high steep three-dimensional structure. The use of new technology of seismic wave scattering theory and high-precision velocity model based on pre-stack time migration and depth migration imaging of seismic data and other high-precision processing technology, in order to identify the southern steep slope of the local structure prediction and analysis of sandstone bedrock surface patterns provide a wealth of information.

旋转轴对称介质中的qP波一阶射线追踪

Elastic anisotropy is a very common phenomenon in the Earth’s interior, especial for sedimentary rock as important gas and oil reservoirs. But in the processing and interpretation of seismic data, it is assumption that the media in the Earth’s interior is completely elastic and isotropic, and then the methods based on isotropy are used to deal with anisotropic seismic data, so it makes the seismic resolution lower and the error on images is caused. The research on seismic wave simulation technology can improve our understanding on the rules of seismic wave propagation in anisotropic media, and it can help us to resolve problems caused by anisotropy of media in the processing and interpretation of seismic data. So researching on weakly anisotropic media with rotated axis of symmetry, we study systematically the rules of seismic wave propagation in this kind of media, simulate the process with numerical calculation, and get the better research results. The first-order ray tracing (FORT) formulas of qP wave derived can adapt to every anisotropic media with arbitrary symmetry. The equations are considerably simpler than the exact ray tracing equations. The equations allow qP waves to be treated independently from qS waves, just as in isotropic media. They simplify considerably in media with higher symmetry anisotropy. In isotropic media, they reduce to the exact ray tracing equations. In contrast to other perturbation techniques used to trace rays in weakly anisotropic media, our approach does not require calculation of reference rays in a reference isotropic medium. The FORT-method rays are obtained directly. They are computationally more effective than standard ray tracing equations. Moreover the second-order travel time corrections formula derived can be used to reduce effectively the travel time error, and improve the accuracy of travel time calculation. The tensor transformation equations of weak-anisotropy parameters in media with rotated axis of symmetry derived from the Bond transformation equations resolve effectively the problems of coordinate transformation caused by the difference between global system of coordinate and local system of coordinate. The calculated weak-anisotropy parameters are completely suitable to the first-order ray tracing used in this paper, and their forms are simpler than those from the Bond transformation. In the numerical simulation on ray tracing, we use the travel time table calculation method that the locations of the grids in the ray beam are determined, then the travel times of the grids are obtained by the reversed distance interpolation. We get better calculation efficiency and accuracy by this method. Finally we verify the validity and adaptability of this method used in this paper with numerical simulations for the rotated TI model with anisotropy of about 8% and the rotated ORTHO model with anisotropy of about 20%. The results indicate that this method has better accuracy for both media with different types and different anisotropic strength. Keywords: weak-anisotropy, numerical simulation, ray tracing equation, travel time, inhomogeneity

井间地震技术研究和应用

Cross well seismic technique is a new type of geophysical method, which observes the seismic wave of the geologic body by placing both the source and receiver in the wells. By applying this method, it averted the absorption to high-frequency component of seismic signal caused by low weathering layers, thus, an extremely high-resolution seismic signal can be acquired. And extremely fine image of cross well formations, structure, and reservoir can be achieved as well. An integrated research is conducted to the high-frequency S-wave and P-wave data and some other data to determine the small faults, small structure and resolving the issues concerning the thin bed and reservoir's connectivity, fluid distribution, steam injection and fracture. This method connects the high-resolution surface seismic, logging and reservoir engineering. In this paper, based on the E & P situation in the oilfield and the theory of geophysical exploration, a research is conducted on cross well seismic technology in general and its important issues in cross well seismic technology in particular. A technological series of integrated field acquisition, data processing and interpretation and its integrated application research were developed and this new method can be applied to oilfield development and optimizing oilfield development scheme. The contents and results in this paper are as listed follows: An overview was given on the status quo and development of the cross well seismic method and problems concerning the cross well seismic technology and the difference in cross well seismic technology between China and international levels; And an analysis and comparison are given on foreign-made field data acquisition systems for cross-well seismic and pointed out the pros and cons of the field systems manufactured by these two foreign companies and this is highly valuable to import foreign-made cross well seismic field acquisition system for China. After analyses were conducted to the geometry design and field data for the cross well seismic method, a common wave field time-depth curve equation was derived and three types of pipe waves were discovered for the first time. Then, a research was conducted on the mechanism for its generation. Based on the wave field separation theory for cross well seismic method, we believe that different type of wave fields in different gather domain has different attributes characteristics, multiple methods (for instance, F-K filtering and median filtering) were applied in eliminating and suppressing the cross well disturbances and successfully separated the upgoing and downgoing waves and a satisfactory result has been achieved. In the area of wave field numerical simulation for cross well seismic method, a analysis was conducted on conventional ray tracing method and its shortcomings and proposed a minimum travel time ray tracing method based on Feraiat theory in this paper. This method is not only has high-speed calculation, but also with no rays enter into "dead end" or "blinded spot" after numerous iterations and it is become more adequate for complex velocity model. This is first time that the travel time interpolation has been brought into consideration, a dynamic ray tracing method with shortest possible path has been developed for the first arrivals of any complex mediums, such as transmission, diffraction and refraction, etc and eliminated the limitation for only traveling from one node to another node and increases the calculation accuracy for minimum travel time and ray tracing path and derives solution and corresponding edge conditions to the fourth-order differential sonic wave equation. The final step is to calculate cross well seismic synthetics for given source and receivers from multiple geological bodies. Thus, real cross-well seismic wave field can be recognized through scientific means and provides important foundation to guide the cross well seismic field geometry designing. A velocity tomographic inversion of the least square conjugated gradient method was developed for cross well seismic velocity tomopgraphic inversion and a modification has been made to object function of the old high frequency ray tracing method and put forward a thin bed oriented model for finite frequency velocity tomographic inversion method. As the theory model and results demonstrates that the method is simple and effective and is very important in seismic ray tomographic imaging for the complex geological body. Based on the characteristics of the cross well seismic algorithm, a processing flow for cross well seismic data processing has been built and optimized and applied to the production, a good section of velocity tomopgrphic inversion and cross well reflection imaging has been acquired. The cross well seismic data is acquired from the depth domain and how to interprets the depth domain data and retrieve the attributes is a brand new subject. After research was conducted on synthetics and trace integration from depth domain for the cross well seismic data interpretation, first of all, a research was conducted on logging constraint wave impedance of cross well seismic data and initially set up cross well seismic data interpretation flows. After it applied and interpreted to the cross well seismic data and a good geological results has been achieved in velocity tomographic inversion and reflection depth imaging and a lot of difficult problems for oilfield development has been resolved. This powerful, new method is good for oilfield development scheme optimization and increasing EOR. Based on conventional reservoir geological model building from logging data, a new method is also discussed on constraining the accuracy of reservoir geological model by applying the high resolution cross well seismic data and it has applied to Fan 124 project and a good results has been achieved which it presents a bight future for the cross well seismic technology.

多波分量地震资料处理解释方法

To deal with some key problems in multi-component seismic exploration, some methods are introduced in this thesis based on reading amounts of papers about multi-component seismic theories and methods. First, to find a solution for the detection of the fracture density and orientation in igneous, carbonate and shale reservoirs, a large amount of which exist in domestic oil fields with low exploration and development degree, a new fast and slow shear waves separation method called Ratio Method based on S-wave splitting theory is discussed in this thesis, through which the anisotropy coefficient as well as fracture parameters such as density and azimuthal angle can be acquired. Another main point in this thesis involves the application of seismic velocity ratio (Vp/Vs) to predict the Hthological parameters of subsurface medium. To deal with the unfeasibility of velocity ratio calculation method based on time ratio due to the usually low single-noise ratio of S-wave seismic data acquired on land, a new method based on detailed velocity analysis is introduced. Third, pre-stack Kirchhoff integral migration is a new method developed in recent years, through which both S and P component seismic data as well as amplitude ratio of P/S waves can be acquired. In this thesis, the research on untilizing the P and S wave sections as well as amplitude ratio sections to interpret low-amplitude structures and lithological traps is carried out. The fast and slow shear wave separation method is then be applied respectively to detect the density and azimuthal angle of fractures in an igneous rock gas reservoir and the coal formation in a coal field. Two velocity ratio-calculating methods are applied respectively in the lithological prediction at the gas and coal field after summarizing a large amount of experimental results draw domestically and abroad. P and S wave sections as well as amplitude ratio sections are used to identify low-amplitude structures and lithological traps in the slope area of a oil-bearing sedimentary basin. The calculated data concerning fracture density and azimuthal angle through the introduced method matches well with the regional stress and actual drilling data. The predicted lithological data reflects the actual drilling data. Some of the low-amplitude and lithological traps determined by Kirchhoff migration method are verified by the actual drilling data. These results indicate that these methods are very meaningful when dealing with complex oil and gas reservoir, and can be applied in other areas.

基于可复制性的独立成分分析——应用于功能磁共振成像数据

This dissertation systematically depicted and improved the application of Independent Component Analysis (ICA) to Functional Magnetic Resonance Imaging (fMRI), following the logic of verification, improvement, extension, and application. The concept of “reproducibility” was the philosophy throughout its four concluded studies. In the “verification” study, ICA was applied to the resting-state fMRI data, verified the resultant components with reproducibility, and examined the consistency of the results from ICA and traditional “seed voxel” method. At the meantime, the limitation of ICA application on fMRI data analysis was presented. In the “improvement” study, an improved ICA algorithm based on reproducibility, RAICAR, was developed to aid some of the limitations of ICA application. RAICAR was able to rank ICA components by reproducibility, determine the number of reliable components, and obtain more stable results. RAICAR provided useful tools for validation and interpretation of ICA results. In the “extension” study, RAICAR as well as the concept of “reproducibility” was extended to multi-subject ICA analysis, and gRAICAR algorithm was developed. gRAICAR allows some variation across subjects, examining common components among subjects. gRAICAR is also capable to detect potential subject grouping on some components. It is a new way for exploratory group analysis on fMRI. In the “application” study, two newly developed methods, RAICAR and gRAICAR, were used to investigate the effect of early music training on the brain mechanism of memory and learning. The results showed brain mechanism difference in memory retrieval and learning process between two groups of subjects. This study also verified the usefulness and importance of the new methods.

An artificial immune system for data analysis

Timmis J and Neal M J. An artificial immune system for data analysis. In Proceedings of 3rd international workshop on information processing in cells and tissues (IPCAT), Indianapolis, U.S.A., 1999.

Accurate Range Image Registration: Eliminating or Modelling Outliers

Liu, Yonghuai, Liu, Honghai, Li, Longzhuang, Wei, Baogang. Accurate Range Image Registration: Eliminating or Modelling Outliers. Proceedings of 12th IEEE Conference on Emerging Technologies and Factory Automation, 2007, pp. 1316-1323. Sponsorship: IEEE

Społeczna interpretacja wybranych wczesnośredniowiecznych cmentarzysk rzędowych w perspektywie gender studies i lifecycle analysis

Wydział Historyczny: Instytut Prahistorii

Radio i jego miejsce w życiu codziennym. Studium odbioru stacji radiowych w Polsce po 1989 roku. Analiza i interpretacja badań jakościowych

Wydział Historyczny: Instytut Etnologii i Antropologii Kulturowej

Prawa człowieka w kontekstach kulturowych

The power of human rights idea and its expansion are connected with the experience of so far unprecedented pain and cruelty caused by man to man during the Second World War. Doctrine of legal positivism strenghtened totalitarian systems. One of the essential goals that were set by totalitarian systems was ethnic cleansing within both one’s and subjugated communities. To achieve this goal, concentration camps were established. This Second World War’s events gave raise to a question: does the common morality of the whole mankind exist? The Nuremberg Trials based on conviction that this common morality of the whole mankind exists. In this lawsuits Nazis were on trials for mass murder and crimes against humanity despite the fact that this crimes did not exist as a criminal offences in international law of that time. Lawyers of Nazis argued that their clients should not have been on trials for crimes against humanity because the rule “lex retro non agit” (“the law does not operate retroactively”) should have been in force. International Military Tribunal dismissed this argument – it was stated they tried Nazis are responsible for acts resulting from breach of the natural law. Therefore, the primacy of natural law over civil law (was approved and they admitted that morality and law are essential components of international reality. Since The Nuremberg Trials, the process of making international relations more ethical proceeded consistently through positivisationi.e. introducing human rights ideas to civil law (this issue is included in the Part I of the book: Positivisation of human rights idea). In this way, contemporary human rights as civil law arose, established on the basis of international agreement. Using them in order to legitimize and validate humanitarian interventions undertaken in various parts of the world became the common standard. However, positivisation of human rights idea did not mean that one common paradigm was accepted. Many interpretation of human rights arose and many new human rights formed in concrete cultures. It gives raise to a question about validity of interventions especially in the context of cultural differences in various parts of the world that influence perception, understanding and interpretation of human rights (this issues are discussed in Part II of this book). At present human rights are not only relativized to cultural contexts but undergo semantic changes as a result of globalisation process as well (Part II of the book: Human rights idea vs globalisation). Moreover, the propositions of establishing institutions and global structures that would strengthen human rights idea appear, interalia new propositions of citizenship defining (ujmowanie jako definiowanie)in response to a decreasing role and significance of nation states in the age of globalization. The idea of human rights dominated present-day law, culture and daily life both in local and global dimension. Human rights issue became essential for philosophy, especially political philosophy.

Filozofia antyczna wobec problemu interpretacji. Rozwój alegorezy od przedsokratyków do Arystotelesa

The present work examines the beginnings of ancient hermeneutics. More specifically, it discusses the connection between the rise of the practice of allegoresis, on the one hand, and the emergence of the first theory of figurative language, on the other. Thus, this book investigates the specific historical and cultural circumstances that enabled the ancient Greeks not only to discover the possibility of allegorical interpretation, but also to treat figurative language as a philosophical problem. By posing difficulties in understanding the enigmatic sense of various esoteric doctrines, poems, oracles and riddles, figurative language created the context for theoretical reflection on the meaning of these “messages”. Hence, ancient interpreters began to ponder over the nature and functions of figurative (“enigmatic”) language as well as over the techniques of its proper use and interpretation. Although the practice of allegorical interpretation was closely linked to the development of the whole of ancient philosophy, the present work covers only the period from the 6th to the 4th century B.C. It concentrates, then, on the philosophical and cultural consequences of allegoresis in the classical age. The main thesis advocated here has it that the ancient Greeks were in-clined to regard allegory as a cognitive problem rather than merely as a stylistic or a literary one. When searching for the hidden meanings of various esoteric doc-trines, poems, oracles and riddles, ancient interpreters of these “messages” assumed allegory to be the only tool suitable for articulating certain matters. In other words, it was their belief that the use of figurative language resulted from the necessity of expressing things that were otherwise inexpressible. The present work has been organized in the following manner. The first part contains historical and philological discussions that provide the point of departure for more philosophical considerations. This part consists of two introductory chapters. Chapter one situates the practice of allegorical interpretation at the borderline of two different traditions: the rhetorical-grammatical and the hermeneutical. In order to clearly differentiate between the two, chapter one distinguishes between allegory and allegoresis, on the one hand, and allegoresis and exegesis, on the other. While pointing to the conventionality (and even arbitrariness) of such distinctions, the chapter argues, nevertheless, for their heuristic usefulness. The remaining part of chapter one focuses on a historical and philological reconstruction of the most important conceptual tools of ancient hermeneutics. Discussing the semantics of such terms as allēgoría, hypónoia, ainigma and symbolon proves important for at least two crucial reasons. Firstly, it reveals the mutual affinity between allegoresis and divination, i.e., practices that are inherently connected with the need to discover the latent meaning of the “message” in question (whether poem or oracle). Secondly, these philological analyses bring to light the specificity of the ancient understanding of such concepts as allegory or symbol. It goes without saying that antiquity employed these terms in a manner quite disparate from modernity. Chapter one concludes with a discussion of ancient views on the cognitive value of figurative (“enigmatic”) language. Chapter two focuses on the role that allegoresis played in the process of transforming mythos into logos. It is suggested here that it was the practice of allegorical interpretation that made it possible to preserve the traditional myths as an important point of reference for the whole of ancient philosophy. Thus, chapter two argues that the existence of a clear opposition between mythos into logos in Preplatonic philosophy is highly questionable in light of the indisputable fact that the Presocratics, Sophists and Cynics were profoundly convinced about the cognitive value of mythos (this conviction was also shared by Plato and Aristotle, but their attitude towards myth was more complex). Consequently, chapter two argues that in Preplatonic philosophy, myth played a function analogous to the concepts discussed in chapter one (i.e., hidden meanings, enigmas and symbols), for in all these cases, ancient interpreters found tools for conveying issues that were otherwise difficult to convey. Chapter two concludes with a classification of various types of allegoresis. Whilst chapters one and two serve as a historical and philological introduction, the second part of this book concentrates on the close relationship between the development of allegoresis, on the one hand, and the flowering of philosophy, on the other. Thus, chapter three discusses the crucial role that allegorical interpretation came to play in Preplatonic philosophy, chapter four deals with Plato’s highly complex and ambivalent attitude to allegoresis, and chapter five has been devoted to Aristotle’s original approach to the practice of allegorical interpretation. It is evident that allegoresis was of paramount importance for the ancient thinkers, irrespective of whether they would value it positively (Preplatonic philosophers and Aristotle) or negatively (Plato). Beginning with the 6th century B.C., the ancient practice of allegorical interpretation is motivated by two distinct interests. On the one hand, the practice of allegorical interpretation reflects the more or less “conservative” attachment to the authority of the poet (whether Homer, Hesiod or Orpheus). The purpose of this apologetic allegoresis is to exonerate poetry from the charges leveled at it by the first philosophers and, though to a lesser degree, historians. Generally, these allegorists seek to save the traditional paideia that builds on the works of the poets. On the other hand, the practice of allegorical interpretation reflects also the more or less “progressive” desire to make original use of the authority of the poet (whether Homer, Hesiod or Orpheus) so as to promote a given philosophical doctrine. The objective of this instrumental allegoresis is to exculpate philosophy from the accusations brought against it by the more conservative circles. Needless to say, these allegorists significantly contribute to the process of the gradual replacing of the mythical view of the world with its more philosophical explanation. The present book suggests that it is the philosophy of Aristotle that should be regarded as a sort of acme in the development of ancient hermeneutics. The reasons for this are twofold. On the one hand, the Stagirite positively values the practice of allegoresis, rehabilitating, thus, the tradition of Preplatonic philosophy against Plato. And, on the other hand, Aristotle initiates the theoretical reflection on figurative (“enigmatic”) language. Hence, in Aristotle we encounter not only the practice of allegoresis, but also the theory of allegory (although the philosopher does not use the term allēgoría). With the situation being as it is, the significance of Aristotle’s work cannot be overestimated. First of all, the Stagirite introduces the concept of metaphor into the then philosophical considerations. From that moment onwards, the phenomenon of figurative language becomes an important philosophical issue. After Aristo-tle, the preponderance of thinkers would feel obliged to specify the rules for the appropriate use of figurative language and the techniques of its correct interpretation. Furthermore, Aristotle ascribes to metaphor (and to various other “excellent” sayings) the function of increasing and enhancing our knowledge. Thus, according to the Stagirite, figurative language is not only an ornamental device, but it can also have a significant explanatory power. Finally, Aristotle observes that figurative expressions cause words to become ambiguous. In this context, the philosopher notices that ambiguity can enrich the language of a poet, but it can also hinder a dialectical discussion. Accordingly, Aristotle is inclined to value polysemy either positively or negatively. Importantly, however, the Stagirite is perfectly aware of the fact that in natural languages ambiguity is unavoidable. This is why Aristotle initiates a syste-matic reflection on the phenomenon of ambiguity and distinguishes its various kinds. In Aristotle, ambiguity is, then, both a problem that needs to be identified and a tool that can help in elucidating intricate philosophical issues. This unique approach to ambiguity and figurative (“enigmatic”) language enabled Aristotle to formulate invaluable intuitions that still await appropriate recognition.