Now the truth of all knowledge rests on the proof of the existence of God. The soul is an imperfect substance, but it has the Idea of an absolute perfect existence within itself; this perfection is not begotten in itself, just because it is an imperfect substance; this Idea is thus innate. In Descartes the consciousness of this fact is expressed by his saying that as long as the existence of God is not proved and perceived the possibility of our deceiving ourselves remains, because we cannot know whether we do not possess a nature ordered and disposed to err (_supra_, p. 226).[170] The form is rather a mistaken one, and it only generally expresses the opposition in which self-consciousness stands to the consciousness of what is different, of the objective; and we have to deal with the unity of both—the question being whether what is in thought likewise possesses objectivity. This unity rests in God, or is God Himself. I shall put these assertions in the manner of Descartes: “Amongst these various conceptions possessed by us there likewise is the conception of a supremely intelligent, powerful, and absolutely perfect Being; and this is the most excellent of all conceptions.” This all-embracing universal conception has therefore this distinguishing feature, that in its case the uncertainty respecting Being which appears in the other conceptions, finds no place. It has the characteristic that “In it we do not recognize existence as something merely possible and accidental, as we do the conceptions of other things which we perceive clearly, but as a really essential and eternal determination. For instance, as mind perceives that in the conception of a triangle it is implied that the three angles are equal to two right angles, the triangle has them; and in the same way from the fact that mind perceives existence to be necessarily and eternally implied in the Notion of the most perfect reality, it is forced to conclude that the most perfect reality exists.”[171] For to perfection there likewise pertains the determination of existence, since the conception of a non-existent is less perfect. Thus we there have the unity of thought and Being, and the ontological proof of the existence of God; this we met with earlier (p. 63, _seq._) in dealing with Anselm.