Philosophy treats of physics where a more careful knowledge is required because the problems which come under this head are numerous... So the reader of Ctesibius or Archimedes and the other writers of treatises of the same class will not be able to appreciate them unless he has been trained in these subjects by the philosophers.

From the exterior face of the wall towers must be projected, from which an approaching enemy may be annoyed by weapons, from the embrasures of those towers, right and left.

For siege works against bold and venturesome men should be constructed on one plan, on another against cautious men, and on still another against the cowardly.

The leaves of these [larch] trees are like those of the pine; timber from them comes in long lengths, is as easily wrought in joiner's work as is the clearwood of fir, and contains a liquid resin, of the color of Attic honey, which is good for consumptives.

The winter oak... is very useful in buildings but when in a moist place it takes in water to its centre... and so it rots. The Turkey oak and the beech both... take in moisture to their centre and soon decay. White and black poplar, as well as willow, linden, and the agnus castus... are of great service from their stiffness... they are a convenient material to use in carving.

I am moreover inclined to be concise when I reflect on the constant occupation of the citizens in public and private affairs, so that in their few leisure moments they may read and understand as much as possible.

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.