One is obliged to confess that perception and what depends on it are inexplicable by mechanical reasons, i.e. in terms of forms and movements. Let's imagine a machine whose structure permits it to think and feel and have perceptions, and go on to enlarge it in our minds, maintaining its proportions, until one could go inside it as into a mill. This being posited, on a visit to its interior one would find nothing but parts pushing against one another, and nothing to explain how perception works. And so it is in the simple substance, and not the composite (i.e. the machine) that we must seek it out. Indeed, perceptions and their alterations are all we find in simple substances. In these alone consist all internal actions of simple substances.
Monadology §17
Monadology §17
