2. THE FIRST ACT OF PHILOSOPHY.—Though the material furnished by experience is the basis of philosophy, yet, since it is furnished, it stands outside of philosophy. The question arises, what is the first act or beginning of philosophy? The thinking should first separate itself from experience, that it may clearly see the difficulties of its undertaking. _The beginning of philosophy_, where the thinking rises above that which is given, is accordingly doubt or _scepticism_. Scepticism is twofold, a lower and a higher. The lower scepticism simply doubts that things are so constituted as they appear to us to be; the higher scepticism passes beyond the form of the phenomenon, and inquires whether in reality any thing there exists. It doubts _e. g._ the succession in time; it asks in reference to the forms of the objects of nature which exhibit design, whether the design is perceived, or only attached to them in the thought, &c. Thus the problems which form the content of metaphysics, are gradually brought out. The result of scepticism is therefore not negative, but positive. Doubt is nothing but the thinking upon those conceptions of experience which are the material of philosophy. Through this reflection, scepticism leads us to the knowledge that these conceptions of experience, though they refer to something given, yet contain no conceivable content free from logical incongruities. 3. REMODELLING OF THE CONCEPTIONS OF EXPERIENCE.—Metaphysics, according to Herbart, is the science of that which is conceivable in experience. Our view thus far has been a twofold one. On the one side we hold fast to the opinion that the single basis of philosophy is experience, and on the other side, scepticism has shaken the credibility of experience. The point now is to transform this scepticism into a definite knowledge of metaphysical problems. Conceptions from experience crowd upon us, which cannot be thoughts, _i. e._ they may indeed be thought by the ordinary understanding, but this thinking is obscure and confused, and does not separate nor compare opposing characteristics. But an acute process of thought, a logical analysis, will find in the conceptions of experience (_e. g._ space, time, becoming, motion, &c.) contradictions and characteristics, which are totally inconsistent with each other. What now is to be done? We may not reject these conceptions, for they are given, and beyond the given we cannot step; we cannot retain them, for they are inconceivable and cannot logically be established. The only way of escape which remains to us is to remodel them. _To remodel the conceptions of experience_, to eliminate their contradictions, is the proper act of speculation. Scepticism has brought to light the more definite problems which involve a contradiction, and whose solution it therefore belongs to metaphysics to attempt; the most important of these are the problems of inherence, change, and the Ego.