The name of Kant will always be intimately connected with the word metaphysics, not because he buried himself in it, as some have supposed who only know his system of philosophy by hearsay; but because his labours consisted in forbidding reason to approach this science which is constantly threatening to invade it, and to get the upper hand by putting itself in its place. Kant was the first to trace with decision the line of demarcation between the knowledge of which our reason is capable, and that of which it is incapable. No one has drawn so sharp a line between the knowable and the unknowable; this was to explain metaphysics. Alfred Fouillée has defined them as “the critical study of problems which the mind seeks to unravel from a necessity of its nature, although another necessity of its nature renders it incapable of solving them”--such is metaphysics. This definition is excellent, but for those who make no preparatory studies in philosophy it would present itself rather in this form. If certain questions are of necessity presented to the mind which it finds it impossible to solve, it follows that the mind would necessarily contradict itself. Thus this succinct definition of Fouillée requires to be itself defined. Noiré, whilst giving more details, is also more exact. “Metaphysics is only explained on the condition that we understand the nature of our power of understanding, in so far as, on the one part, this power is actively manifested in experience, and secondly, in so far as it possesses anteriorly to any experience, and to anything observed, certain ideas without which there could not possibly or even conceivably, be any impression made in the human mind.” I am afraid that this explanation of Noiré will also be lost upon those who are not experienced in the subject. The explanation of Schopenhauer is not less definite, and is more concise than the two preceding. The foundation upon which all our knowledge and all our science rests, is the incomprehensible--I fancy that the uninitiated will be equally unable to understand this. It is not surprising. Philosophers speak a language of their own, which must be learnt before it can be understood, which is the case with all languages. Kant develops this thesis with greater simplicity and clearness. “As long as the human intellect moves in the sphere of the senses and of experience it is safe; this sphere is very vast; it is there that all phenomena may be known which appears in space and time, that is to say, all belonging to the phenomenal world in which we live. But if the intellect rebels against the gaoler which holds it captive in the magic circle, breaks its chains and enters into the region of ideals, it will err.”