all visible objects are at some distance from the eye, is yet unable to determine the relative distances at which they stand towards it and towards one another. In the words of Mr Bailey, "Whether objects are seen to be external, or at some distance, is one question altogether distinct from the inquiry—whether objects are seen by the unassisted vision to be at different distances from the percipient." He then adds, "Yet Berkeley uniformly assumes them to be the same, or at least takes it for granted that they are to be determined by the same arguments." This is true enough in one sense, but Mr Bailey should have considered that if Berkeley did not make the discrimination, it was because he conceived that the opinion which maintained the absolute non-externality of visible objects (i.e., of objects in relation to the organ of sight) was the only question properly at issue. The remark, however, is valuable, because Berkeley's followers, Reid, Stewart, and others, have supposed that the other question was the one to be grappled with; and, accordingly, they have not ventured beyond maintaining that the eye is unable to judge of the different degrees of distance at which objects may be placed from it. But the thoroughgoing opinion is the true one, and the followers have deserted their leader only to err, or to discover truths of no scientific value or significance whatever.
Let us now consider the general object which Berkeley had in view, and determine the proper point of sight from which his "theory of vision" should be
