Notes on Leibniz thought experiment

Gottfried Wilhelm Leibniz, Monadology (1714), §17 [1]: “Besides, it must be admitted that perception, and anything that depends on it, cannot be explained in terms of mechanistic causation – that is, in terms of shapes and motions. Let us pretend that there was a machine, which was constructed in such a way as to give rise to thinking, sensing, and having perceptions. You could imagine it expanded in size (while retaining the same proportions), so that you could go inside it, like going into a mill. On this assumption, your tour inside it would show you the working parts pushing each other, but never anything which would explain a perception. So perception is to be sought, not in compounds (or machines), but in simple substances. Furthermore, there is nothing to be found in simple substances, apart from perceptions and their changes. Again, all the internal actions of simple substances can consist in nothing other than perceptions and their changes.”