One of the classical Utopias of philosophy is the City of the Sun by Tommaso Campanella, which outlined an ideal community based upon a marvelous Arcadian city encompassing seven levels of advanced humanity.

Utopian groups had emigrated into space to found their ideal communities... and it was on such a colony world, called appropriately Arcadia, that the recontact starship "Daedalus" made its fourth planetfall. And there, in all its perfect splendor, stood the fulfillment of Campanella's dream, the real seven-circled City of the Sun.

But the city was too literal, the inhabitants too perfect, the world too Arcadian - and very quickly the "Daedalus's" scientists realized that in this Utopia the idealists had unleashed a phenomenon that could undermine all human culture on all human worlds.