Consistency is found in that work whose whole and detail are suitable to the occasion. It arises from circumstance, custom, and nature.

In setting out the walls of a city the choice of a healthy situation is of the first importance: it should be on high ground, neither subject to fogs nor rains; its aspects should be neither violently hot nor intensely cold, but temperate in both respects.

Architects should be educated, skillful with the pencil, instructed in geometry, know much history, have followed the philosophers with attention, understand music, have some knowledge of medicine, know the opinions of the jurists, and be acquainted with astronomy and the theory of the heavens

With the ripening of the fruits in Autumn the leaves begin to wither and the trees, taking up their sap from the earth through the roots, recover themselves and are restored to their former solid texture. But the strong air of winter compresses and solidifies them.

From food and water, then, we may learn whether sites are naturally unhealthy or healthy.

A harmonious design requires that nothing be added or taken away.

Next I must tell about the machine of Ctesibius, which raises water to a height.