Astrology is a science which has had an uncertain status throughout its history, from its beginnings in Greco-Roman Antiquity to the medieval Islamic world and Christian Europe which led to frequent debates about its validity and what kind of a place it should have, if any, in various cultures. Written in the second century A.D., Ptolemy’s Tetrabiblos is not the earliest surviving text on astrology. However, the complex defense given in the Tetrabiblos will be treated as an important starting point because it changed the way astrology would be justified in Christian and Muslim works and the influence Ptolemy’s presentation had on later works represents a continuation of the method introduced in the Tetrabiblos. Abū Ma‘shar’s Kitāb al-Madkhal al-kabīr ilā ‘ilm akām al-nujūm, written in the ninth century, was the most thorough surviving defense from the Islamic world. Roger Bacon’s Opus maius, although not focused solely on advocating astrology, nevertheless, does contain a significant defense which has definite links to the works of both Abū Ma‘shar and Ptolemy. As such, he demonstrates another stage in the development of astrology. These three works together reveal the threads of a trend of a rationalized astrology separated from its mythical origins which began with Ptolemy and survived through both medieval Islam and medieval Europe. In the two examples of defending astrology I have used, Abū Ma‘shar and Roger Bacon, Ptolemy’s influence can be seen to have persisted from the second century through to the thirteenth, and the nature of the differences in their defenses illustrates the continuation and evolution of the tradition of defending astrology.

Astrology is a science which has had an uncertain status throughout its history, from its beginnings in Greco-Roman Antiquity to the medieval Islamic world and Christian Europe which led to frequent debates about its validity and what kind of a place it should have, if any, in various cultures. Written in the second century A.D., Ptolemy’s Tetrabiblos is not the earliest surviving text on astrology. However, the complex defense given in the Tetrabiblos will be treated as an important starting point because it changed the way astrology would be justified in Christian and Muslim works and the influence Ptolemy’s presentation had on later works represents a continuation of the method introduced in the Tetrabiblos. Abū Ma‘shar’s Kitāb al-Madkhal al-kabīr ilā ‘ilm akām al-nujūm, written in the ninth century, was the most thorough surviving defense from the Islamic world. Roger Bacon’s Opus maius, although not focused solely on advocating astrology, nevertheless, does contain a significant defense which has definite links to the works of both Abū Ma‘shar and Ptolemy. As such, he demonstrates another stage in the development of astrology. These three works together reveal the threads of a trend of a rationalized astrology separated from its mythical origins which began with Ptolemy and survived through both medieval Islam and medieval Europe. In the two examples of defending astrology I have used, Abū Ma‘shar and Roger Bacon, Ptolemy’s influence can be seen to have persisted from the second century through to the thirteenth, and the nature of the differences in their defenses illustrates the continuation and evolution of the tradition of defending astrology.

The subject of this thesis is Roger Bacon`s work De signis. Its goal is to consider in what sense Bacon works out the general theory of signs. In this sense the thesis` method is situated in the field of "archeology of sings". First it examines Bacon`s definition of sign as a relation, investigates its formal properties and ways of application in particular cases, i.e. Bacon`s classification of signs. Then it shows the way in which Bacon applies this general notion in particular examinations, that is in problems of what the words signify, concept of univaocation and equivocation, theory of analogy and last but not least it considers a question of the nature of signification itself. The last chapter is dedicated to the examination of the (re)imposition phenomenon together with consideration of result it has on the notion of sign relation`s nature and how it serves as an explanation of the process in which these relations work. Keywords: Roger Bacon, John Deely, Charles S. Peirce, medieval semiotics, archeology of signs.

Before the publication of David Hockney’s book Secret Knowledge: rediscovering the lost techniques of the Old Masters in 2001, it was commonly believed that the first artist to use an optical aid in painting was the seventeenth-century Dutch painter Johannes Vermeer. Hockney, however, believes that the use of projected images started much earlier, as early as the fifteenth-century, claiming that evidence can be found in the work of the Flemish painter Jan van Eyck. Without rejecting Hockney’s pioneering work in this field, I nevertheless make the perhaps bolder claim that Italian artists were using the aid of image projections even before the time of Jan van Eyck, that is, as early as 1270. Although much of the information required to make an earlier claim for the use of optics can be found in Hockney’s publication, the key to linking all the information together has been missing. It is my unique contention that this key is a letter that has always been believed to have been European in origin. More commonly referred to as Roger Bacon’s Letter I show in detail how this letter was, in fact, not written by Roger Bacon, but addressed to him, and that this letter originated in China. Chinese knowledge about projected images, that is the concept that light-pictures could be received onto appropriate supports, came directly to Europe around 1250. This knowledge was expanded upon by Roger Bacon in his Opus Majus, a document which arrived in Italy in 1268 for the special consideration of Pope Clement IV. The medieval Italian painter Cimabue was able to benefit directly from this information about optical systems, when he himself was in Rome in 1272. He immediately began to copy optical projections, which stimulated the creation of a new, more individualistic, mode of representation in Italian painting from this time forward. The notion that projected images greatly contributed towards the development of naturalism in medieval Italian painting replaces the previously weak supposition that the stimulation was classical or humanist theory, and shows that it was, in fact, far likely something more technical as well. / Art History / D.Litt. et Phil. (Art History)

Before the publication of David Hockney’s book Secret Knowledge: rediscovering the lost techniques of the Old Masters in 2001, it was commonly believed that the first artist to use an optical aid in painting was the seventeenth-century Dutch painter Johannes Vermeer. Hockney, however, believes that the use of projected images started much earlier, as early as the fifteenth-century, claiming that evidence can be found in the work of the Flemish painter Jan van Eyck. Without rejecting Hockney’s pioneering work in this field, I nevertheless make the perhaps bolder claim that Italian artists were using the aid of image projections even before the time of Jan van Eyck, that is, as early as 1270. Although much of the information required to make an earlier claim for the use of optics can be found in Hockney’s publication, the key to linking all the information together has been missing. It is my unique contention that this key is a letter that has always been believed to have been European in origin. More commonly referred to as Roger Bacon’s Letter I show in detail how this letter was, in fact, not written by Roger Bacon, but addressed to him, and that this letter originated in China. Chinese knowledge about projected images, that is the concept that light-pictures could be received onto appropriate supports, came directly to Europe around 1250. This knowledge was expanded upon by Roger Bacon in his Opus Majus, a document which arrived in Italy in 1268 for the special consideration of Pope Clement IV. The medieval Italian painter Cimabue was able to benefit directly from this information about optical systems, when he himself was in Rome in 1272. He immediately began to copy optical projections, which stimulated the creation of a new, more individualistic, mode of representation in Italian painting from this time forward. The notion that projected images greatly contributed towards the development of naturalism in medieval Italian painting replaces the previously weak supposition that the stimulation was classical or humanist theory, and shows that it was, in fact, far likely something more technical as well. / Art History / D.Litt. et Phil. (Art History)

Translations of works containing Arabic and ancient Greek knowledge of the philosophical and mechanical underpinnings of the natural world—a field of study called natural philosophy—were disseminated throughout twelfth-century England. During the twelfth and thirteenth centuries, institutional (ecclesiastical/university) scholars received and further developed this natural philosophical knowledge by reconciling it with Christian authoritative sources (the Bible and works by the Church Fathers). The subsequent discourse that developed demonstrated ambivalence towards natural philosophical knowledge; institutional scholars expressed both acceptance and anxiety regarding the theory and practice of alchemy, astrology/astronomy, and humoral/astrological medicine. While the institutional development and discourse surrounding natural philosophical thought is well-represented within medieval scholarship, an examination of the transmission and reception of this institutional discourse by broader sectors of English medieval society is needed. Examining fourteenth- and fifteenth-century Middle English public writings, texts, and copies of Latin works provides an important avenue of analysis when exploring the transmission and reception of institutional natural philosophical discourse to the laity. By comparing the similarities of discourse evident between the institutional and lay texts and the textual approaches the Middle English writers employed to incorporate this discourse, these works demonstrate that the spheres of institutional and lay knowledge traditionally separated by medieval historians overlapped as the clerics and laity began sharing a similar understanding of the philosophical underpinnings of the natural world.