ну вот знаменитый финал обмена разумов (сильно сокращенный в русском переводе) и Лейбница теория
http://www.scribd.com/doc/35996274/Robert-Sheckley-MindswapStanhope, if not the best of all possible worlds, was still the best world Marvin had seen. It was a place where you could live without things jumping out at you, and without your jumping out at things. No metaphoric deformationwas possible in Stanhope; a cow looked exactly like a cow, and to call it anything else was unwarrantable poetic licence .And so, undoubtedly: east, west, home's the best: and Marvin set himself the task of enjoyment of the familiar, which sentimental wise men say is the apex of human wisdom.
His life was marred only by one or two small doubts. First and foremost was the question: How had he come back to Earth from the Twisted World?
He did considerable research on this question, which was more ominous thanit first seemed. He realized that nothing is impossible in the Twisted World, and that nothing is even improbable. There is causality in the Twisted World, but there is also noncausality. Nothing must be; nothing is necessary
( далее ) Про Лейбница:
The phrase "the best of all possible worlds" (French: le meilleur des mondes possibles; German: Die beste aller möglichen Welten) was coined by the German polymath Gottfried Leibniz in his 1710 work Essais de Théodicée sur la bonté de Dieu, la liberté de l'homme et l'origine du mal (Essays on the Goodness of God, the Freedom of Man and the Origin of Evil). The claim that the actual world is the best of all possible worlds is the central argument in Leibniz's theodicy, or his attempt to solve the problem of evil.
http://en.wikipedia.org/wiki/Best_of_all_possible_worlds