Vitruvius iterum et Frontinus à Iocundo revisi repurgatique quantum ex collatione licuit

...of the arcades and the leveled plain, and in pipes, natural spirits are produced in different ways; no one will be able to remedy the faults of these unless he knows the principles of the nature of things from philosophy. Likewise, one who reads the books of Ctesibius or Archimedes, and others who have written down precepts of this kind, will not be able to agree with them unless he has been instructed in these matters by philosophers. It is fitting that he should know music, so that he may be acquainted with canonical and mathematical principles, and furthermore, that he might be able to correctly make the adjustments for ballistae, catapults, and scorpions. For in the capitals on the right and left, there are holes for the hemitonia half-tones/tensions, through which ropes are stretched from twisted sinews; these are not blocked or tied off until they make sounds that are taut and equal to the ears of the craftsmen. For the arms that are enclosed in these tensions, when they are extended, must emit the blow equally and together. If they are not in homotonia equal pitch/tension, they will hinder the straight firing of projectiles. Likewise, in theaters, bronze vessels that are placed under the steps according to mathematical principles, and the distinctions of sounds which the Greeks call echeia sounding vessels, are composed for musical harmonies or concerts, divided in the arrangement of the fourth, the fifth, and the octave, so that when the voice, encountering the sound, strikes them in the arrangements, it arrives at the ears of the spectators clearer and sweeter, increased by the increment. No one will be able to make hydraulic machines and other things similar to these instruments without musical principles. Furthermore, it is necessary to know the discipline of medicine because of the inclinations of the heavens, which the Greeks call climata zones/latitudes, and the airs...