Thus it is that because rulers instead of inducing their subjects to be virtuous are wickedly jealous of their virtue and hinder it as much as they can, very few virtuous men are found under tyrants. For as Aristotle says, "brave men are found where brave men are honored, " and Cicero says, "what is despised by everyone decays and ceases to grew." It is natural that men who are brought up in fear should become servile in spirit and cowardly in the face of any difficult or strenuous endeavor. So the Apostle [Paul] says "Fathers, do not provoke your children to indignation lest they become discouraged." King Solomon had these evil effects of tyranny in mind when he said "When the wicked reign it is the ruination of men" because the wickedness of tyranny leads their subjects to fall away from the perfection of virtue.
St. Thomas Aquinas, On Kingship, ch. 3.