In the Republic (519 E ff.), having finished his account of the education of the philosopher king, and having described the ideal life of pure contemplation in the Simile of the Cave, Plato makes Socrates say:

Then it will be our function as founders, I said, to compel the best natures to undertake the study which we previously declared to be the highest, to observe the good, and to make that ascent we mentioned, and when they have done so and looked their fill, then we must not allow them that freedom which they now possess.