It must be confessed, moreover, that perception, and that which depends on it are inexplicable by mechanical causes, that is, by figures and motions. And, supposing there were a machine so constructed as to think, feel and have perception, we could conceive of it as enlarged and yet preserving the same proportions, so that we ight enter it as a mill. And this granted, we should only find on visiting it, pieces which push one against another, but never anything by which to explain a perception. This must be sought for, therefore, in the simple substance and not in the composite or in the machine.