[144] For the same relation that the mind bears to the outward [74] sense, that same does science bear towards art; for, as has been said before, the soul is as it were the outward sense of the outward sense; therefore each of them has attracted to itself some slight things of nature, concerning which it labours and occupies itself, geometry having appropriated lines, and music sounds, and philosophy the whole nature of existing things. For this world is its subject matter, and so is the whole essence, both visible and invisible, of existing things.