  It was claimed above that Leibniz does not explicitly adopt the kind of possible-worlds semantics endorsed by Lewis and others in his own definitions and explanations of our basic modal concepts. But it is easy to show that Leibniz's account of these modal concepts can be translated into the now standard possible-worlds semantics. Consider the way Leibniz distinguishes necessary and contingent truths in §13 of the Discourse on Metaphysics.