Plato’s Republic, Book V

“Unless either philosophers govern in cities, or those who are at present called kings and governors philosophize genuinely and sufficiently, and these two, the political power and philosophy, unite in one; and unless the bulk of those who at present pursue each of these separately are of necessity excluded from either, there shall be no end, Glauco, to the miseries of cities, nor yet, as I imagine, to those of the human race; nor till then, shall ever this republic, which we have gone over in our reasonings, spring up to a possibility, and behold the light of the sun.”