There remains the answer to the same question as regards the objects of Metaphysics. These objects are according to Kant inferences, and illegitimate inferences. They are not necessary elements or factors in the constitution of experience. In order that there should be experience, knowledge, science, there must be an endless hold of space and time in which to stow it clearly and distinctly away: and there must also be ties and relations binding it part to part, links of reference and correlation, a sort of logical elastic band that will stretch to include infinitely copious materials. But each real knowledge attaches to a definite assignable perception, in a single place and time. From this point we can travel--by means of like points--practically without limit in any direction. But though the old margin fades forever and forever as we move, a new margin takes its place: the limitation and finitude remain: and new acquisitions are always balanced in part by the loss of the old. Yet the heart and the imagination are clamorous, and the intellect is ready to serve them. Such an intellect Kant has called Reason, and its products (Platonic) 'Ideas.' The (Platonic) Idea expresses not so much an object of knowledge as a postulate, a problem, an act of faith. The 'Vaulting ambition' Intelligence 'o'erleaps itself and falls on t'other,' Unsatisfied with a bundle of sensations and ideas, it demands their abiding unity in a substantial Soul. To simplify the endlessness of physical phenomena, it sums them up in a Universe. To gather all mental and physical diversities and divisions into one life, it creates the ideal of God. Each single experience, and the collected aggregate of these experiences, is felt to fall short of a complete total: and yet this complete total, the ultimate unity, is itself not an experience at all. But, if it be no object of experience, it is still an idea on which reason is inevitably driven: and the attempt to apprehend it, in the absence of experience, gives rise to the theories of Metaphysics. Everything, however, which can be in the strict sense of the word known, must be perceived in space and time, or, in other words, must lie open to experience. Where experience ends, human reason meets a barrier which checks any efficient progress, but refuses to recognise the check as due to a natural limit which it is really impossible to pass. The idea of completeness, of a rounded system, or unconditional unity, is still left, after the categories of the understanding have done their best: and is not destroyed although its realisation or explication is declared to be impossible.