But how is white distinguished from black? Sensation or intelligence tell us that those things are different without informing us of their reason; either sensation, because its function is not to set forth the reason of things, but only to bring them somehow to our attention; or intelligence, because it discerns things that are simple by intuition, without having to resort to ratiocination, and limits itself to the statement that something is such or such. Besides, in each one of the operations of intelligence there is a difference (a special distinctive characteristic) which enables it to distinguish different things, without this difference (which is proper to each of the operations of intelligence) itself having need to be discerned by the help of some other difference. SOME QUALITIES ARE DIFFERENCES. Are all qualities differences, or not? Whiteness, colors, qualities perceived by touch and taste, may become differences between different objects, though they themselves be species. But how do the sciences of grammar or of music constitute differences? The science of grammar renders the mind grammatical, and the science of music renders the mind musical, especially if they be untaught; and these thus become specific differences. Besides, we have to consider whether a difference be drawn from the same genus (from which the considered things are drawn), or from some other genus. If it be drawn from the same genus, it fulfils, for the things of this genus, the same function as does a quality to the quality to which it serves as difference. Such are virtue and vice; virtue is a particular habit, and vice is also a particular habit; consequently, as habits are qualities, the differences of these habits (either of virtue or vice) will be qualities. It may perhaps be objected that a habit without difference is not a quality, and that it is the difference alone which constitutes the quality.[409] We will answer that it is (commonly) said that sweet is good, and that bitter is bad; this then implies a recognition of their difference by a habit (a manner of being), and not by a quality. What if sweet be said to be "crude," or thick and bitter, thin or refined? The answer is that coarseness does not inform us of the nature of sweetness, but indicates a manner of being of what is sweet; and similarly, with what is refined. THERE ARE DIFFERENCES WHICH ARE NOT QUALITIES.