It is important to observe, as much to prevent an equivoke into which many fall, as because of the consequences that will follow from holding it, that we must not look upon the perceptive knowledge of reality that surrounds us as a firm basis, upon which we act, by translating the formed volition into act. For were this so, we should have to assume that the surrounding world, perceived by the spirit, stops after the perceptive act, which is not the case. That world changes every second, the perceptive act perceives the new and the different, and the volitional act changes according to that real and perceived change. Perception and volition alternate every instant; in order to will, we must touch the earth at every instant, in order to resume force and direction. [Sidenote: _No other theoretic precedent._] Continuous perception and continuous change, that is the necessary theoretic condition of volition. It is necessary and unique. No other theoretical element is needed, because every other is contained in it, and beyond it no other is thinkable. [Sidenote: _Critique of concepts and practical judgments._] But if this be true and no other theoretic element save that precede the volition, then we find in the aforesaid theory the criticism of a series of other theories, generally admitted in the Philosophy of the practical, not less than in ordinary thought, none of which can be retained without alterations and corrections. Or better, there are not so many various theories to criticize; there is rather one theory, which presents itself under different aspects and assumes various names. This theory consists substantially in affirming that with the complex of cognitions, of which we have hitherto treated (all of which are summed up in the historical judgment), we do not yet possess that one which is necessary, before we can proceed to volition and action. A special form of concepts and judgments which can be called _practical,_ must, it is said, appear; these render the will possible, by interposing themselves between the previous merely historical judgment and the will. Is it not indubitable that we possess practical concepts, that is, concepts of classes of action or of supreme guides to action, concepts of things _good, of ideals, of ends,_ and that we effect _judgments_ of value by the application of those concepts to the image of given actions? Is it not indubitable that those judgments and those concepts refer, not to the simple present fact, but to the future? How could we will, if we did not know what is good to will, and that a given possible action corresponds to that concept of good? [Sidenote: _Posteriority of judgments to the practical act._]