Pantheon symbolizing the cosnos would, he thought, appropriate How should the parts o such august buildings be proportioned? Vitruvius supplied the answer. His famous c of human proportions should b reflected in those of temples and churches. Vitruvius(see p. 185) described how a well-built man fits with extended arms and legs into the most perfect geometrical figures, the circle and square. This simple concept seemed to contain some deep and fundamental truth and it haunted the imagination of architects and artists Indeed it had been present, intermit tently, in many minds since the Middle Ages. The Christian mystic, Hildegard Bingen(1098-1179), for instance, referred to it and illustrations of it appeared in illuminated manuscripts her works. But its importance for architects was compelling Renaissance and in about 1485-9o Leonardo made a drawing of it with a translation into Italian of Vitruvius's Latin text appended in his own hand(11.20) During these years he and Bramant were working for the sforza duke of Milan, and Bramante presumably knew this drawing as well as the numerous projects for centrally planned and domed churches that Leonardo made at the same time. Though none foreshadows the Tempietto precisely, Bramante's debt to Leonardo evident. Their association remained close after they both left Milan in 15oo, and when Leonardo visited Rome in 1504 he may well have contributed to the conception of the Tempietto.