and causality. How small is the share of the senses in perception, compared with that of the intellect, is also shown by a comparison of the nerve apparatus for receiving impressions with that for working them up. The mass of the nerves of sensation of the whole of the organs of sense is very small compared with that of the brain, even in the case of the brutes, whose brain, since they do not, properly speaking, i.e., in the abstract, think, is merely used for effecting perception, and yet when this is complete, thus in the case of mammals, has a very considerable mass, even after the cerebellum, whose function is the systematic guidance of movements, has been taken away.
That excellent book by Thomas Reid, the "Inquiry into the Human Mind" (first edition, 1764; 6th edition, 1810), as a negative proof of the Kantian truths, affords us a very thorough conviction of the inadequacy of the senses to produce the objective perception of things, and also of the non-empirical origin of the perception of space and time. Reid refutes Locke's doctrine that perception is a product of the senses, by a thorough and acute demonstration that the collective sensations of the senses do not bear the least resemblance to the world as known in perception, and especially that the five primary qualities of Locke (extension, form, solidity, movement, and number) absolutely could not be afforded us by any sensation of the senses. Accordingly he gives up the question as to the mode of origination and the source of perception as completely insoluble; and although altogether unacquainted with Kant, he gives us, as it were, according to the regula falsi, a thorough proof of the intellectual nature of perception (really first explained by me as a consequence of the Kantian doctrine), and also of the a priori source, discovered by Kant, of its constituent elements, space, time, and causality, from which those primary qualities of Locke first proceed, but by means of which they are easily constructed. Thomas Reid's book is very instructive and well worth reading – ten times more so than all the philosophy together that has
