"That the understanding," Kant says, "can never make a transcendental, but only an empirical use, either of its _a priori_ principles, or of its conceptions, is a principle which, if known with conviction, leads to the most important consequences. The transcendental use of a conception in any principle, consists in referring it to things, _in general, and in themselves_; whilst the empirical use is in referring the conception to phenomena alone, that is, to the objects of a possible experience, by which we may easily see that this latter use is the only one that can stand. To every conception is necessary, first of all, a logical form of a conception in general, of the thought: and secondly, the possibility of subjecting to it an object, to which it may refer; but without this object it wants all sense, it contains nothing, although it may involve the logical function necessary to form a conception by means of certain data. The object cannot be given to a conception except in intuition; and although pure intuition may be _a priori_ possible before the object, it cannot, however, receive its object, and consequently its objective value, otherwise than by the empirical intuition of which it is the form. All conceptions and with them all principles, although they be possible _a priori_, do, notwithstanding, refer to empirical intuitions, that is, to data of possible experience. _Without this they have no objective value; they are nothing but a mere play, whether of the imagination or of the understanding_, with the respective representations of the one or the other faculty. * * * * * "That the same is the case with all the categories and principles formed from them, is apparent from this, that we cannot really define a single one of them; that is to say, we cannot render the possibility of their object intelligible without attending to the conditions of sensibility, and consequently to the form of the appearances; conditions to which these categories must be confined as to their sole objects. If this condition be taken away, all meaning, that is, all relation to the object is destroyed, and by no example can we be made to conceive what is the proper meaning of these conceptions. * * * * * "If no account be made of all the conditions of sensibility which denote them (he is speaking of the categories) as conceptions of a possible empirical use, if they be taken to be conceptions of things in general, and consequently, of transcendental use, nothing remains to be done, so far as they are concerned, but to preserve the logical functions in judgments, as the condition of the possibility of the things themselves, without being able to show in what case, their application and their object, and consequently they themselves, may, in the pure understanding, and without the intervention of sensibility, have a meaning and an objective value. * * * * *