The Republic by Plato Part 3 Page 11

On your views, we must not admit them.

On my views, if you like to father them on me; that we must not admit them is certain.

Again, truth should be highly valued; if, as we were saying, a lie is useless to the gods, and useful only as a medicine to men, then the use of such medicines should be restricted to physicians; private individuals have no business with them.

Clearly not, he said.

Then if any one at all is to have the privilege of lying, the rulers of the State should be the persons; and they, in their dealings either with enemies or with their own citizens, may be allowed to lie for the public good. But nobody else should meddle with anything of the kind; and although the rulers have this privilege, for a