Why Does Leibniz Reject Empiricism?

Why does Leibniz reject empiricism? Even do that Leibniz was not only a mathematician, physicist, a public figure and a philosopher, he is mostly known as the founder and developer of Different and Integration Calculus on the hand with Isaac Newton.

But his achievements and merits in other sciences and basically in philosophy are of the same importance as in mathematics.

He was a bright representative of rationalism: a philosophical outlook that stated that the only objective sources of knowledge are human