He proposes his theory that the universe is made of an infinite number of simple substances known as monads .
Leibniz 's best known contribution to metaphysics is his theory of monads , as exposited in Monadologie .
Leibniz proposes Leibniz 's theory that the universe is made of an infinite number of simple substances known monads monads .
Leibniz 's best known contribution to metaphysics is his theory of monads , as exposited in Monadologie .