Let us also consider again that other utterance of Professor Huxley's, with which I began this chapter. According to the positive view of morals, he says, those special sets of happiness that a moral system selects for us, have no more to do with any theory as to the reason of their selection, than a man's sight has to do with his theory of vision, or than the hot taste of ginger has to do with a knowledge of its analysis. That is a most clear and succinct statement of the whole positive position; and we shall now be able to profit by its clearness, and to see how all that it does is to reveal confusion. In the first place, Professor Huxley's comparisons really illustrate the very fact that he designs them to invalidate. It is precisely on his theory of vision that a man's sight practically does depend. All sight, so far as it conveys any meaning to him, is an act of inference; and though generally this process may be so rapid that it is not perceived by him, yet the doubt often felt about distant or unusual objects will make him keenly conscious of it. Whilst as to ginger and the taste produced by it, the moral question is not whether it is hot or not; but whether or no it will be for our advantage to eat it; and this resolves itself into two further questions; firstly, whether its heat is pleasant, and secondly whether its heat is wholesome. On the first of these Professor Huxley throws no light whatever; whilst as to the second, it really hangs entirely on the very point that he cited as indifferent. We must have some knowledge, even though it be only vague and negative, of the nature of a food, before we know whether it will be well for us in the long run to habitually eat it, or to abstain from it.