The truth is that the human mind never transcends the reality in which it lives. Indeed, it has no need to transcend it, seeing that this world contains everything that is required for its own explanation. If philosophers declare themselves finally content when they have deduced the world from principles which they borrow from experience and then transplant into an hypothetical Beyond, the same satisfaction ought to be possible, if these same principles are allowed to remain in this world to which they belong anyhow. All attempts to transcend the world are purely illusory, and the principles transplanted into the Beyond do not explain the world any better than the principles which are immanent in it. When thought understands itself, it does not demand any such transcendence at all, for there is no thought-content which does not find within the world a perceptual content, in union with which it can form a real object. The objects of imagination, too, are contents which have no validity, until they have been transformed into ideas that refer to a perceptual content. Through this perceptual content they have their place in reality. A concept the content of which is supposed to lie beyond the world which is given to us, is an abstraction to which no reality corresponds. Thought can discover only the concepts of reality; in order to find reality itself, we need also perception. An Absolute Being for which we invent a content, is a hypothesis which no thought can entertain that understands itself. Monism does not deny ideal factors; indeed, it refuses to recognise as fully real a perceptual content which has no ideal counterpart, but it finds nothing within the whole range of thought that is not immanent within this world of ours. A science which restricts itself to a description of percepts, without advancing to their ideal complements, is, for Monism, but a fragment. But Monism regards as equally fragmentary all abstract concepts which do not find their complement in percepts, and which fit nowhere into the conceptual net that embraces the whole perceptual world. Hence it knows no ideas referring to objects lying beyond our experience and supposed to form the content of purely hypothetical Metaphysics. Whatever mankind has produced in the way of such ideas Monism regards as abstractions from experience, whose origin in experience has been overlooked by their authors.