224. Whence then the singularity we have noticed in this principle? It is neither evident, nor demonstrable; it is necessary to all others, and whoever denies them is refuted by it. Whence, then, such a singularity? It has a very simple cause; it is, that the principle of evidence expresses no objective truth, and therefore is not demonstrable: it is not a simple fact of consciousness, for it expresses the relation of the subject to the object, for which reason it cannot be limited to the purely subjective; it is a proposition known by a reflex act, and it expresses the primary law of all our objective cognitions. These are founded on evidence; this we experience: but when the mind asks why we trust evidence, we can make no other answer than that whatever is evident is true. What is the foundation of this proposition? Ordinarily it has none; we conform to it without ever thinking of it; but if we take the pains to reflect, we find three motives for assenting to it: the first is an irresistible instinct of nature; the second is the destruction of all our cognitions and the impossibility of thought, if we do not admit the legitimacy of the criterion; the third is the perceiving that, admitting this criterion, every thing is co-ordinated in the intellect, that an ideal universe admirably harmonized, takes the place of chaos, and that we feel possessed of the means necessary to reason and to construct a scientific edifice in the real universe, the knowledge of which we have from experience.(22) CHAPTER XXIII. THE CRITERION OF CONSCIOUSNESS. 225. Having established the worth of the principles of consciousness, of evidence, and of contradiction, in relation to the dignity of fundamental, we will now examine the intrinsic value of the different criteria. And here the doctrine of the preceding chapters, of which the following are the development and complement, furnishes much light. We will begin with consciousness, or the internal sense. The testimony of consciousness includes all phenomena, either actively or passively, realized in our soul. It is by its nature purely subjective; so that in itself considered, apart from the intellectual instinct and the light of evidence, it testifies nothing with respect to objects. By it we know what we experience, not what is; we perceive the phenomenon, not the reality; what authorizes us to say: such a thing appears to me; but not, such a thing is. The transition from subject to object, from the idea representing to the thing represented, from the impression to the cause impressing, belongs to other criteria: consciousness is limited to the interior, or rather, to itself, which is nothing but an act of our soul. 226. We must distinguish between direct and reflex consciousness: the former accompanies every internal phenomenon; the latter does not: the former is natural; the latter philosophical: the former abstracts the act of reason; the latter is one of these acts.