In the third place, it is difficult, if not impossible, to read the _Deduction_ without realizing that Kant failed to distinguish knowing from that formation of mental imagery which accompanies knowing. The process of synthesis, if it is even to seem to constitute knowledge and to involve the validity of the categories, must really be a process by which we construct, and recognize our construction of, an individual reality in nature out of certain physical data. Nevertheless, it is plain that what Kant normally describes as the process of synthesis is really the process by which we construct an imaginary picture of a reality in nature not present to perception, i. e. by which we imagine to ourselves what it would look like if we were present to perceive it. This is implied by his continued use of the terms 'reproduction' and 'imagination' in describing the synthesis. To be aware of an object of past perception, it is necessary, according to him, that the object should be _re_produced. It is thereby implied that the object of our present awareness is not the object of past perception, but a mental image which copies or reproduces it. The same implication is conveyed by his use of the term 'imagination' to describe the faculty by which the synthesis is effected; for 'imagination' normally means the power of making a mental image of something not present to perception, and this interpretation is confirmed by Kant's own description of the imagination as 'the faculty of representing an object even without its presence in perception'.[37] Further, that Kant really fails to distinguish the construction of mental imagery from literal construction is shown by the fact that, although he insists that the formation of an image and reproduction are both necessary for knowledge, he does not consistently adhere to this. For his general view is that the elements combined and recognized as combined are the original data of sense, and not reproductions of them which together form an image, and his instances imply that the elements retained in thought, i. e. the elements of which we are aware subsequently to perception, are the elements originally perceived, e. g. the parts of a line or the units counted.[38] Moreover, in one passage Kant definitely describes certain _objects_ of _perception_ taken together as an _image_ of that 'kind' of which, when taken together, they are an instance. "If I place five points one after another, . . . . . this is an image of the number five."[39] Now, if it be granted that Kant has in mind normally the process of imagining, we can see why he found no difficulty in the thought of knowledge as construction. For while we cannot reasonably speak of making _an object of knowledge_, we can reasonably speak of making _a mental image_ through our own activity, and also of making it in accordance with the categories and the empirical laws which presuppose them. Moreover, the ease with which it is possible to take the imagining which accompanies knowing for knowing[40]--the image formed being taken to be the object known and the forming it being taken to be the knowing it--renders it easy to transfer the thought of construction to the knowledge itself. The only defect, however, under which the view labours is the important one that, whatever be the extent to which imagination must accompany knowledge, it is distinct from knowledge. To realize the difference we have only to notice that the process by which we present to ourselves in imagination realities not present to perception presupposes, and is throughout guided by, the knowledge of them. It should be noted, however, that, although the process of which Kant is normally thinking is doubtless that of constructing mental imagery, his real view must be that knowledge consists in constructing a world out of the data of sense, or, more accurately, as his instances show, out of the objects of isolated perceptions, e. g. parts of a line or units to be counted. Otherwise the final act of recognition would be an apprehension not of the world of nature, but of an image of it.