The Republic by Plato Part 5 Page 33

common meals. None of them will have anything specially his or her own; they will be together, and will be brought up together, and will associate at gymnastic exercises. And so they will be drawn by a necessity of their natures to have intercourse with each other — necessity is not too strong a word, I think?

Yes, he said; — necessity, not geometrical, but another sort of necessity which lovers know, and which is far more convincing and constraining to the mass of mankind.

True, I said; and this, Glaucon, like all the rest, must proceed after an orderly fashion; in a city of the blessed, licentiousness is an unholy thing which the rulers will forbid.

Yes, he said, and it ought not to be permitted.