who settled in the island state of Cos, and there opened a school. Afterwards Antipater pursued the subject; then there was Archinapolus, who also left rules for casting nativities, based not on the moment of birth but on that of conception.” After listing a number of natural philosophers and other astronomers and astrologers, Vitruvius concludes: “Their learning deserves the admiration of mankind; for they were so solicitous as even to be able to predict, long beforehand, with divining mind, the signs of the weather which was to follow in the future.”[865] [Sidenote: Divergence between theory and practice, learning and art.] Such a passage demonstrates plainly enough Vitruvius’ full confidence in the art of casting nativities and of weather prediction, but it has no integral connection with his practical architecture or even any necessary connection with the construction of a sun-dial, which is what he is actually driving at. But Vitruvius believed that an architect should not be a mere craftsman but broadly educated in history, medicine, and philosophy, geometry, music, and astronomy, in order to understand the origin and significance of details inherited from the art of the past, to assure a healthy building, proper acoustics, and the like. It is in an attempt to air his learning and in the theoretical portions of his work that he is prone to occult science. But the practical processes of architecture and military engineering are free from it. [Sidenote: Evils in contemporary learning.]