must be, facts which no blind person could form any conception of. He accordingly determined to construct, or at least to pave the way towards the construction of, a truer theory of vision, in which these—the proper and peculiar facts of the sense—should be taken exclusively into account: and hence, passing from the mathematical and physiological method, he took up a different, and what we have called a purely speculative ground—a ground which cannot be rendered intelligible or conceivable to the blind, inasmuch as they are deficient in the sense which alone furnishes the data that are to be dealt with. The test by which Berkeley tried optical science was, Can the blind be brought to understand, or to form any conception of it? If they can, then the science must be false, for it ought to be a science of experiences from which they are entirely debarred. We should bear in mind, then, first of all, that his object in constructing his theory of vision was, leaving all geometrical and anatomical considerations out of the question, to apprehend the proper and peculiar facts of sight—the facts, the whole facts, and nothing but the facts, of that particular and isolated sense.
Now we think that Mr Bailey's leading error consists in his not having remarked the unswerving devotedness with which Berkeley follows out this aim, and hence, having failed to appreciate the singleness and unrelaxing perseverance of his purpose, he has consequently failed to appreciate the great success which has attended his endeavours. He has not
