Music, also, the architect ought to understand so that he may have knowledge of the canonical and mathematical theory, and besides be able to tune ballistae , catapultae, and scorpiones to the proper key. For to the right and left in the beams are the holes in the frames through which the strings of twisted sinew are stretched by means of windlasses and bars, and these strings must not be clamped and made fast until they give the same correct note to the ear of the skilled workman.

In accordance with the foregoing investigations on mathematical principles, let bronze vessels be made, proportionate to the size of the theatre, and let them be so fashioned that, when touched, they may produce with one another the notes of the fourth, the fifth, and so on up the double octave.

Thus by such victory, not by machines but in oppositions to the principle to the principles of machines, has the freedom of states been preserved by the cunning of architects.

In all matters but particularly in architecture, that which is signified is the subject of which we may be speaking and that which gives significance is a demonstration on scientific principles. One who professes himself an architect should be well versed in both directions.

Some have held that there are only four winds: Solanus from the east; Auster from the south; Favonius from due west; Septentrio from the north. But more careful investigators tell us that there are eight.

All machinery is derived from nature, and is founded on the teaching and instruction of the revolution of the firmament.

In the midst of all this great variety of subjects, an individual cannot attain to perfection in each, because it is scarcely in his power to take in and comprehend the general theories of them.