It should probably not be surprising that Leibniz's explication of the nature of the distinction between necessary and contingent truths can be translated into the terms of contemporary possible-worlds semantics. For Leibniz tells us in On Freedom (De libertate... 1689?) that he first came to think of the nature of possibilia in terms of fictional worlds, worlds that have existence in a somewhat tenuous sense. “But the consideration of possibles, which are not, were not, and will not be, brought