M. Tullius Cicero, De Officiis
Walter Miller, Ed.

[64] But the mischief is that from this exaltation and greatness of spirit spring all too readily self-will and excessive lust for power. For just as Plato tells us that the whole national character of the Spartans was on fire with passion for victory, so, in the same way, the more notable a man is for his greatness of spirit, the more ambitious he is to be the foremost citizen, or, I should say rather, to be sole ruler. But when one begins to aspire to pre-eminence, it is difficult to preserve that spirit of fairness which is absolutely essential to justice. The result is that such men do not allow themselves to be constrained either by argument or by any public and lawful authority; but they only too often prove to be bribers and agitators in public life, seeking to obtain supreme power and to be superiors through force rather than equals through justice. But the greater the difficulty, the greater the glory; for no occasion arises that can excuse a man for being guilty of injustice.