Our theory of truth, to begin with, supplies the possibility of distinguishing certain truths as “self-evident” in a sense which ensures infallibility. When a belief is true, we said, there is a corresponding fact, in which the several objects of the belief form a single complex. The belief is said to constitute “knowledge” of this fact, provided it fulfils those further somewhat vague conditions which we have been considering in the present chapter. But in regard to any fact, besides the knowledge constituted by belief, we may also have the kind of knowledge constituted by “perception” (taking this word in its widest possible sense). For example, if you know the hour of the sunset, you can at that hour know the fact that the sun is setting: this is knowledge of the fact by way of knowledge of “truths”; but you can also, if the weather is fine, look to the west and actually see the setting sun: you then know the same fact by the way of knowledge of “things.”