art as impious because it was thought to excite absurd and obscene thoughts; this was a sensational, but ultimately not a fatal skirmish. Erasmus of Rotterdam and other humanists, Protestant and Catholic, had also chastised practitioners of the art of memory for making extravagant claims for its efficacy, although they themselves believed firmly in a well-disposed, orderly memory as an essential tool of productive thought. One explanation for the steady decline in the importance of the art of memory from the 16th to the 20th century is offered by the late Ioan P. Culianu, who argued that it was suppressed during the Reformation and Counter-Reformation when Protestants and reactionary Catholics alike worked to eradicate pagan influence and the lush visual imagery of the Renaissance. Whatever the causes, in keeping with general developments, the art of memory eventually came to be defined primarily as a part of Dialectics, and was assimilated in the 17th century by Francis Bacon and René Descartes into the curriculum of Logic, where it survives to this day as a necessary foundation for the teaching of Argument. Simplified variants of the art of memory were also taught through the 19th century as useful to public orators, including preachers and after-dinner speakers. Principles Visual sense and spatial memory Perhaps the most important principle of the art is the dominance of the visual sense in combination with the orientation of 'seen' objects within space. This principle is reflected in the early Dialexis fragment on memory, and is found throughout later texts on the art. Mary Carruthers, in a review of Hugh of St. Victor's Didascalion, emphasizes the importance of the visual sense as follows: Even what we hear must be attached to a visual image. To help recall something we have heard rather than seen, we should attach to their words the appearance, facial expression, and gestures of the person speaking as well as the appearance of the room. The speaker should therefore create strong visual images, through expression and gesture, which will fix the impression of his words. All the rhetorical textbooks contain detailed advice on declamatory gesture and expression; this underscores the insistence of Aristotle, Avicenna, and other philosophers, on the primacy and security for memory of the visual over all other sensory modes, auditory, tactile, and the rest. This passage emphasizes the association of the visual sense with spatial orientation. The image of the speaker is