Monism is never called upon to ask whether there are any principles of explanation for reality other than percepts and concepts. The Monist knows that in the whole realm of the real there is no occasion for this question. In the perceptual world, as immediately apprehended, he sees one-half of reality; in the union of this world with the world of concepts he finds full reality. The Metaphysical Realist might object that, relatively to our organisation, our knowledge may be complete in itself, that no part may be lacking, but that we do not know how the world appears to a mind organised differently from our own. To this the Monist will reply, Maybe there are intelligences other than human; and maybe also that their percepts are different from ours, if they have perception at all. But this is irrelevant to me for the following reasons. Through my perceptions, i.e., through this specifically human mode of perception, I, as subject, am confronted with the object. The nexus of things is thereby broken. The subject reconstructs the nexus by means of thought. In doing so it re-inserts itself into the context of the world as a whole. As it is only through the Self, as subject, that the whole appears rent in two between percept and concept, the reunion of those two factors will give us complete knowledge. For beings with a different perceptual world (e.g., if they had twice our number of sense-organs) the nexus would appear broken in another place, and the reconstruction would accordingly have to take a form specifically adapted to such beings. The question concerning the limits of knowledge troubles only Naïve and Metaphysical Realism, both of which see in the contents of mind only ideal representations of the real world. For, to these theories, whatever falls outside the subject is something absolute, a self-contained whole, and the subject's mental content is a copy which is wholly external to this absolute. The completeness of knowledge depends on the greater or lesser degree of resemblance between the representation and the absolute object. A being with fewer senses than man will perceive less of the world, one with more senses will perceive more. The former's knowledge will, therefore, be less complete than the latter's. For Monism, the situation is different. The point where the unity of the world appears to be rent asunder into subject and object depends on the organisation of the percipient. The object is not absolute but merely relative to the nature of the subject. The bridging of the gap, therefore, can take place only in the quite specific way which is characteristic of the human subject. As soon as the Self, which in perception is set over against the world, is again re-inserted into the world-nexus by constructive thought, all further questioning ceases, having been but a result of the separation.