If we insist on considering it in its isolation, we probably eke it out in thought by an unarticulated affirmation such as that which constitutes an impersonal judgment; in other words, we affirm it to belong to reality under some condition which remains unspecified. Thus the linguistic form of the relative clause, as also the separate existence of the spoken or written word, produces an illusion which has governed the greater part of logical theory so far as concerns the separation between concept and judgment, _i.e._ between entertaining ideas and affirming them in reality. In our waking life, all thought is judgment, every idea is referred to reality, and in being so referred, is ultimately affirmed of reality. The separation of elements in the texture of Judgment into Subjects and Predicates which, as separated, are conceived as _possible_ Subjects and Predicates, is therefore {74} theoretical and ideal, an analysis of a living tissue, not an enumeration of loose bricks out of which something is about to be built up. _The kind of ideas which can claim truth_ (iii.) “Idea” has two principal meanings. (_a_) A psychical presentation and (_b_) An identical reference. This distinction is the same as that between our course of ideas and our world of knowledge. We must try now to define it more accurately. (_a_) An idea as a psychical presentation is strictly a particular. Every moment of consciousness is full of a given complex of presentation which passes away and can never be repeated without some difference. For this purpose a representation is just the same as a presentation; is, in fact, a presentation. Its detail at any given moment is filled in by the influence of the moment, and it can never occur again with precisely the same elements of detail as before. If we use the term “idea” in this sense, as a momentary particular mental state, it is nonsense to speak of having the same idea twice, or of referring it to a reality other than our mental life. The idea in this sense is a psychical image. We cannot illustrate this usage by any recognisable part of our mental furniture, for every such part which can be described and indicated by a general name, is something more than a psychical image. We can only say that that which at any moment we have in consciousness, when our waking perception encounters reality, is such an idea, and so too is the image supplied by memory, when considered simply as a datum, a fact, in our mental history.