In addition to general principles, the other kind of self-evident truths are those immediately derived from sensation. We will call such truths “truths of perception,” and the judgements expressing them we will call “judgements of perception.” But here a certain amount of care is required in getting at the precise nature of the truths that are self-evident. The actual sense-data are neither true nor false. A particular patch of colour which I see, for example, simply exists: it is not the sort of thing that is true or false. It is true that there is such a patch, true that it has a certain shape and degree of brightness, true that it is surrounded by certain other colours. But the patch itself, like everything else in the world of sense, is of a radically different kind from the things that are true or false, and therefore cannot properly be said to be true . Thus whatever self-evident truths may be obtained from our senses must be different from the sense-data from which they are obtained.