177. This crucial question in regard to extension does not seem even to have suggested itself to Berkeley. The reason why is not far to seek. Professor Fraser, in his valuable edition, represents him as meaning by visible extension ‘coloured experience in sense,’ and by tangible extension ‘resistent experience in sense.’ [1] No fault can be found with this interpretation, but the essential question, which Berkeley does not fairly meet, is whether the experience in each case is complete in a single feeling or consists in a succession of feelings. If in a single feeling, it clearly is not extension, as a relation between parts, at all; if in a succession of feelings, it is only extension because a synthetic principle, which is not itself one of the feelings, but equally present to them all, transforms them into permanent parts of which each qualifies the other by outwardness to it. Berkeley does not see the necessity of such a principle, because he allows himself to suppose extension--at any rate visible extension--to be constituted by a single feeling. Having first pronounced that the proper object of sight is colour, he quietly substitutes for this _situations_ of colour, degrees of strength and faintness in colour, and quantities of coloured points, as if these, interchangeably with mere colour, were properly objects of sight and perceived in single acts of vision. Now if by object of sight were meant something other than the sensation itself--something which to a thinking being it suggests as its cause--there would be no harm in this language, but neither would there be any ground for saying that the proper object of sight is colour, for distinguishing visible from tangible extension, or for denying that the outwardness of body to body is seen. Such restrictions and distinctions have no meaning, unless by sight is meant the nervous irritation, the affection of the visual organ, as it is to a merely feeling subject; yet in the very passages where he makes them, by saying that we see situations and degrees of colour, and quantities of coloured points, Berkeley converts sight into a judgment of extensive and intensive quantity. He thus fails to discern that the transition from colour to coloured extension cannot be made without on the one hand either the presentation of successive pictures or (which comes to the same) successive acts of attention to a single picture, and on the other hand a synthesis of the successive presentations as mutually qualified parts of a whole. In other words, he ignores the work of thought involved in the constitution alike of coloured and tangible extension, and in virtue of which alone either is extension at all. [1] See Fraser’s Berkeley, ‘Theory of Vision,’ note 42. I may here say that I have gone into less detail in my account of Berkeley’s system than I should otherwise have thought necessary, because Professor Fraser has supplied, in the way of explanation of it, all that a student can require.