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 inquiry, 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
delicately defined, are not fitted to furnish us with any such perception, or to aid us in making any such discrimination. See 'Müller's Physiology,' translated by W. Baly, M.D., vol. ii pp. 1073, 1074. Although the application of Treviranus's discovery to the refutation of Dr Brown's reasoning is our own, we may remark, in justice to an eminent philosopher, that it was Sir William Hamilton who first directed our attention to the fact as established by that great physiologist.
