Thought contributes this content to the percept from the world of concepts and ideas. In contrast with the content of perception which is given to us from without, the content of thought appears within our minds. The form in which thought first appears in consciousness we will call "intuition." Intuition is to thoughts what observation is to percepts. Intuition and observation are the sources of our knowledge. An external object which we observe remains unintelligible to us, until the corresponding intuition arises within us which adds to the reality those sides of it which are lacking in the percept. To anyone who is incapable of supplying the relevant intuitions, the full nature of the real remains a sealed book. Just as the colour-blind person sees only differences of brightness without any colour qualities, so the mind which lacks intuition sees only disconnected fragments of percepts. To explain a thing, to make it intelligible, means nothing else than to place it in the context from which it has been torn by the peculiar organisation of our minds, described above. Nothing can possibly exist cut off from the universe. Hence all isolation of objects has only subjective validity for minds organised like ours. For us the universe is split up into above and below, before and after, cause and effect, object and idea, matter and force, object and subject, etc. The objects which, in observation, appear to us as separate, become combined, bit by bit, through the coherent, unified system of our intuitions. By thought we fuse again into one whole all that perception has separated. An object presents riddles to our understanding so long as it exists in isolation. But this is an abstraction of our own making and can be unmade again in the world of concepts. Except through thought and perception nothing is given to us directly. The question now arises as to the interpretation of percepts on our theory. We have learnt that the proof which Critical Idealism offers for the subjective nature of percepts collapses. But the exhibition of the falsity of the proof is not, by itself, sufficient to show that the doctrine itself is an error. Critical Idealism does not base its proof on the absolute nature of thought, but relies on the argument that Naïve Realism, when followed to its logical conclusion, contradicts itself. How does the matter appear when we recognise the absoluteness of thought?