something, and causes a change of perceptions.

Leibnitz differs from Locke in maintaining that perception is
inexplicable and inconceivable on mechanical principles. It is
always the act of a simple substance, never of a compound. And
"in simple substances there is nothing but perceptions and their
changes." [20]

[Footnote 20: _Menadol_. 17.]

He differs from Locke, furthermore, on the question of the origin of
ideas. This question, he says, "is not a preliminary one in
philosophy, and one must have made great progress to be able to
grapple successfully with it."--"Meanwhile, I think I may say, that
our ideas, even those of sensible objects, _viennent de notre propre
fond_... I am by no means for the _tabula rasa_ of Aristotle; on the
contrary, there is to me something rational (_quelque chose de solide_)
in what Plato called _reminiscence_. Nay, more than that, we have
not only a reminiscence of all our past thoughts, but we have also a
_presentiment_ of all our thoughts." [21]

[Footnote 21: _Reflexions sur l'Essai de l'Entendement humain_.]

Mr. Lewes, in his "Biographical History of Philosophy," speaks of
the essay from which these words are quoted, as written in "a
somewhat supercilious tone." We are unable to detect any such
feature in it. That trait was wholly foreign from Leibnitz's nature.
"Car je suis des plus dociles," he says of himself, in this same
essay. He was the most tolerant of philosophers. "Je ne meprise
presque rien."--"Nemo est ingenio minus quam ego censorio."--