The tyrant, who in order to hold his power, suppresses every superiority, does away with good men, forbids education and light, controls every movement of the citizens and, keeping them under a perpetual servitude, wants them to grow accustomed to baseness and cowardice, has his spies everywhere to listen to what is said in the meetings, and spreads dissension and calumny among the citizens and impoverishes them, is obliged to make war in order to keep his subjects occupied and impose on them permanent need of a chief.
These two rational faculties may be designated the Scientific Faculty and the Calculative Faculty respectively; since calculation is the same as deliberation, and deliberation is never exercised about things that are invariable, so that the Calculative Faculty is a separate part of the rational half of the soul.
Music has the power of producing a certain effect on the moral character of the soul, and if it has the power to do this, it is clear that the young must be directed to music and must be educated in it.
The virtues [moral excellence] therefore are engendered in us neither by nature nor yet in violation of nature; nature gives us the capacity to receive them, and this capacity is brought to maturity by habit.