If we imagine a "machine whose structure makes it think, sense, and have perceptions" enlarged to the size of a mill, upon "inspecting its interior, we will only find parts that push one another, and we will never find anything to explain a perception"
The Principles of Philosophy, or, the Monadology
Leibniz, G. W. <u>Philosophical Essays</u>. Ed. and Trans. Roger Ariew and Daniel Garber. Indianapolis and Cambridge: Hackett Publishing Co., 1989.