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1843.] ascertained that we derive nothing from the eye whatever but sensations of colour—that the idea of extension [he means in its three dimensions] is derived from sensations not in the eye, but in the muscular part of our frame." Thus, contrary to what Mr Bailey affirms, these two philosophers limit the office of vision to the perception of mere colour or difference of colour, denying to the eye the original perception of extension in any dimension whatever. In their estimation, the intuition of space is no more involved in our perception of different colours than it is involved in our perception of different smells or different sounds. Dr Brown's doctrine, in which Mr Mill seems to concur, is, that the perception of superficial extension no more results from a certain expanse of the optic nerve being affected by a variety of colours than it results from a certain expanse of the olfactory nerve being affected by a variety of odours. So much for Mr Bailey's assertion, that all philosophers admit the perception of extension in two dimensions.

But, of course, our main business is with the expression of his own opinion. In rebutting our charge, he maintains that "the visibility of angular distance (that is of extension laterally) is assumed, by implication, as part of Berkeley's doctrine, in almost every chapter of my book."—( Letter, p. 13.) That word almost is a provident saving clause; for we undertake to show that not only is the very reverse assumed, by implication, as part of Berkeley's doctrine, in the single chapter to which we confined our remarks, but that, in another part of his work, it is expressly avowed as the only alternative by which, in the author's opinion, Berkeley's consistency can be preserved.

At the outset of his enquiry, Mr Bailey divides his discussion into two branches: first, Whether objects are originally seen to be external, or at any distance at all from the sight; and, secondly, Supposing it admitted that they are seen to be external, or at some distance from the sight, whether they are all seen in the same plane, or equally near. It was to the former of these questions that we exclusively confined our remarks; and it was in reference to it, and to an important argument evolved by Mr Bailey in the course of its discussion, that we charged him with fathering on Berkeley the doctrine which he now disavows as his interpretation of the bishop's opinion. He further disputes the relevancy of the question about our perception of lateral extension, and maintains that distance in a direction from the percipient, or what we should call protensive distance, is the only matter in dispute; and that it is a misconception of the scope of Berkeley's essay to imagine otherwise. The relevancy of the question shall be disposed of afterwards. In the mean time, the question at issue is, Can the allegation which we have laid to Mr