as an example). This makes it clear that though the architectural mnemonic with its buildings, niches and three-dimensional images was a major theme of the art as practiced in classical times, it often employed signs or notae and sometimes even non-physical imagined spaces. During the period of migration of barbarian tribes and the transformation of the Roman empire the architectural mnemonic fell into disuse. However the use of tables, charts and signs appears to have continued and developed independently. Mary Carruthers has made it clear that a trained memory occupied a central place in late antique and medieval pedagogy, and has documented some of the ways in which the development of medieval memorial arts was intimately intertwined with the emergence of the book as we understand it today. Examples of the development of the potential inherent in the graphical mnemonic include the lists and combinatory wheels of the Majorcan Ramon Llull. The Art of Signs (Latin Ars Notoria) is also very likely a development of the graphical mnemonic. Yates mentions Apollonius of Tyana and his reputation for memory, as well as the association between trained memory, astrology and divination. She goes on to suggest It may have been out of this atmosphere that there was formed a tradition which, going underground for centuries and suffering transformations in the process, appeared in the Middle Ages as the Ars Notoria, a magical art of memory attributed to Apollonius or sometimes to Solomon. The practitioner of the Ars Notoria gazed at figures or diagrams curiously marked and called 'notae' whilst reciting magical prayers. He hoped to gain in this way knowledge, or memory, of all the arts and sciences, a different 'nota' being provided for each discipline. The Ars Notoria is perhaps a descendant of the classical art of memory, or of that difficult branch of it which used the shorthand notae. It was regarded as a particularly black kind of magic and was severely condemned by Thomas Aquinas. Textual mnemonic Carruthers's studies of memory suggest that the images and pictures employed in the medieval arts of memory were not representational in the sense we today understand that term. Rather, images were understood to function "textually", as a type of 'writing', and not as something different from it in kind. If such an assessment is correct, it suggests that the use of text to recollect memories was, for medieval practitioners, merely a variant