The appearance of knowing is never offered to us as a purely subjective fact; that is to say, when we think we know, we think we know something either within or without us, according to the matters which occupy us. Supposing, then, the phenomenon of cognition to be purely subjective, and to become objective for itself, we should have what would constantly lead us into error; for the human reason would be infected with a radical vice, which would oblige it to view these phenomena as means of perceiving the truth, whereas they are only eternal sources of deception. 153. There may arise a doubt in this correspondence of general with particular truth, as to which is the principle; that is, whether general truth is truth by means of particular truths, or the contrary. "All the diameters of a circle are equal;" this is a general truth. If we suppose a circle to exist, all its diameters will be equal. We have already seen that the certainty of the general truth neither does nor can reach us through the particular truth; but neither, on the other hand, does the particular stand in need of the general; so that it seems, that even when we abstract all intelligence, capable of perceiving this general truth, the existing circle will not cease to have all its diameters equal. 154. Moreover, if the truth fail in one single instance, it cannot be general; but the particular may be true although it fail in general. The equality of the diameters of an existing circle is, then, a condition necessary to the general truth; but the general truth is not necessary to the equality of the diameters. It is true in general that all diameters are equal, since this is verified in all either existing or possible, and the general truth is only the expression of this verification; but yet it does not appear that the diameters, in any one particular case, are equal by reason of the general truth. It is true that one particular whole is greater than one of its parts, although considered in itself, abstracted from all general truth; but it would not be true that the whole is greater than one of its parts, if in any one particular whole, the axiom should fail. 155. It would seem that from these observations we could infer that the truth of principles depends upon the truth of facts, and not _vice versa_. Nevertheless, if we reflect more upon this matter, we shall discover that truth is not based upon particular facts, but upon something superior to them. I. We cannot from a particular fact infer a universal truth; but from universal truth we can infer the truth of all particular existing or possible facts. The reason why this consequence is legitimate is found in the necessary connection of the predicate and subject; and this necessity cannot be discovered in particular facts of their own nature contingent.