[47] The “I think” is, as has been already stated, an empirical proposition, and contains the proposition, “I exist.” But I cannot say, “Everything, which thinks, exists”; for in this case the property of thought would constitute all beings possessing it, necessary beings. Hence my existence cannot be considered as an inference from the proposition, “I think,” as Descartes maintained—because in this case the major premiss, “Everything, which thinks, exists,” must precede—but the two propositions are identical. The proposition, “I think,” expresses an undetermined empirical intuition, that perception (proving consequently that sensation, which must belong to sensibility, lies at the foundation of this proposition); but it precedes experience, whose province it is to determine an object of perception by means of the categories in relation to time; and existence in this proposition is not a category, as it does not apply to an undetermined given object, but only to one of which we have a conception, and about which we wish to know whether it does or does not exist, out of, and apart from this conception. An undetermined perception signifies here merely something real that has been given, only, however, to thought in general—but not as a phenomenon, nor as a thing in itself (noumenon), but only as something that really exists, and is designated as such in the proposition, “I think.” For it must be remarked that, when I call the proposition, “I think,” an empirical proposition, I do not thereby mean that the Ego in the proposition is an empirical representation; on the contrary, it is purely intellectual, because it belongs to thought in general. But without some empirical representation, which presents to the mind material for thought, the mental act, “I think,” would not take place; and the empirical is only the condition of the application or employment of the pure intellectual faculty. Thus, then, appears the vanity of the hope of establishing a cognition which is to extend its rule beyond the limits of experience—a cognition which is one of the highest interests of humanity; and thus is proved the futility of the attempt of speculative philosophy in this region of thought. But, in this interest of thought, the severity of criticism has rendered to reason a not unimportant service, by the demonstration of the impossibility of making any dogmatical affirmation concerning an object of experience beyond the boundaries of experience. She has thus fortified reason against all affirmations of the contrary. Now, this can be accomplished in only two ways. Either our proposition must be proved apodeictically; or, if this is unsuccessful, the sources of this inability must be sought for, and, if these are discovered to exist in the natural and necessary limitation of our reason, our opponents must submit to the same law of renunciation and refrain from advancing claims to dogmatic assertion.