The elimination of ethics, then, as a system of precepts, involves no intrinsic difficulties other than those involved in the admission of a natural science that can account for the moralisation of man. The discovery, however, that our assertions of moral obligation are merely the expression of an ineffectual wish to be better off than we are, or are due to the survival of habits originally enforced by physical fear, but of which the origin is forgotten, is of a kind to give us pause. It logically carries with it the conclusion, however the conclusion may be disguised, that, in inciting ourselves or others to do anything because it ought to be done, we are at best making use of a serviceable illusion. And when this consequence is found to follow logically from the conception of man as in his moral attributes a subject of natural science, it may lead to a reconsideration of a doctrine which would otherwise have been taken for granted as the most important outcome of modern enlightenment. As the first charm of accounting for what has previously seemed the mystery of our moral ature passes away, and the spirit of criticism returns, we cannot but enquire whether a being that was merely a result of natural forces could form a theory of those forces as explaining himself. We have to return once more to that analysis of the conditions of knowledge, which forms the basis of all Critical Philosophy whether called by the name of Kant or no, and to ask whether the experience of connected matters of fact, which in its methodical expression we call science, does not presuppose a principle which is not itself any one or number of such matters of fact, or their result. (§8 ¶1)

Can the knowledge of nature be itself a part or product of nature, in that sense of nature in which it is said to be an object of knowledge? This is our first quesiton. If it is answered in the negative, we shall at least have satisfied ourselves that man, in respect of the function called knowledge, is not merely a child of nature. We shall have ascertained the presence in him of a principle not natural, and a specific function of this principle in rendering knowledge possible. The way will then be so far cleared for the further question which leads us, in the language of Kant, from the Critique of Speculative to that of Practical Reason: the question whether the same principle has not another expression than that which appears in the determination of experience and through it in our knowledge of a world—an expression which consists in the consciousness of a moral ideal and the determination of human action thereby. (§8 ¶2)