The Republic by Plato Part 8 Page 81

Yes, that may be expected.

And the tyrant, if he means to rule, must get rid of them; he cannot stop while he has a friend or an enemy who is good for anything.

He cannot.

And therefore he must look about him and see who is valiant, who is high-minded, who is wise, who is wealthy; happy man, he is the enemy of them all, and must seek occasion against them whether he will or no, until he has made a purgation of the State.

Yes, he said, and a rare purgation.

Yes, I said, not the sort of purgation which the physicians make of the body; for they take away the worse and leave the better part, but he does the reverse.

If he is to rule, I suppose that he cannot help himself.