History of the Peloponnesian War

And so by these means our city is seldom at rest, but is involved in many feuds and conflicts—not more frequently with its enemies than with itself—and sometimes in tyrannies and unprincipled cabals. But I will endeavour, if only you will follow my advice, to let none of these things occur in our time;

by convincing you who form the mass of the people, and by chastising those who plot such things; not only when convicted in the act, (for it is difficult so to catch them,) but also for what they have the wish, though not the power, to do. For we must avenge ourselves on our enemy, not only for what he does, but beforehand also, for his intention to do it; inasmuch as if we are not first in guarding against him, we shall be first in suffering. With regard to the oligarchs, on the other hand, I shall reprove them on some points, watch them on others, and warn them on others; for in this way I think I shall best deter them from their evil practices. And, indeed, what is it (a question which I have often asked) that ye really wish, ye young men?