De Architectura, Book IX, Vitruvius
- De Architectura, Book IX: Chapter VI, Paragraph 3: "When we come to natural philosophy, however, Thales of Miletus, Anaxagoras of Clazomenae, Pythagoras of..."
- De Architectura, Book IX: Introduction, Paragraph 2: "What does it signify to mankind that Milo of Croton and other victors of his..."
Book IX of De Architectura concerns sciences influencing architecture (geometry, mensuration, astronomy, sundial).