gods. And those who repay what has been lent to them, and restore what has been deposited with them, act justly as to men. And those who pay due respect to the tombs, clearly are pious towards the dead. There is, therefore, one justice towards the Gods, a second towards men, and a third towards the dead.
XLIX. In the same way, there are also three species of knowledge. There is one kind which is practical, a second which is productive, a third which is theoretical. For the science of building houses or ships, is production. For one can see the work which is produced by it. Political science, and the science of playing the flute, or the harp, or such things as that, is practical; for one cannot see any visible result which has been produced by them, and yet they are doing something. For one man plays the flute or plays the harp, and another occupies himself with state affairs. Again, geometrical, and harmonic, and astronomical science are all theoretical, for they do nothing, and produce nothing. But the geometrician theorizes as to what relation lines bear to one another; and the harmonist speculates about sounds, and the astronomer about stars and about the world. Accordingly, of sciences some are theoretical, others productive, and a third species is practical.