is the inquiry into right and wrong to proceed? Shall we interrogate nature? Dive into history, anthropology, evolutionary science? Or shall we fall back upon introspection, the interrogation of our own minds?
Here it is that the fundamental distinction to which I have referred comes in, a distinction which the following illustration will best explain. How are the principles of pure mathematics, as, for instance, of arithmetic, arrived at? Being self-evident, they are reached by us intuitively, by an operation of the mind within itself. When, however, the merchant, who desires to calculate his probable profits, applies to his business the abstract principles of number, he has to deal also with such concrete facts as the state of the markets and the weight of his goods ; and these, not being self-evident, can be ascertained only by observation and experience. His practical conclusions, therefore, are based upon two wholly distinct classes of truths—abstract principles and concrete facts—which require for their investigation entirely different methods.
Now in ethical inquiries, I conceive, a closely analogous distinction should constantly be observed. First, we have to examine in the abstract the underlying principles which determine the moral quality of conduct (or perhaps, more strictly, of the feelings which prompt the conduct); and secondly, taking in the concrete a particular case or class of cases, we have to decide into what moral category it falls. Nor does it seem unreasonable to hold that for these two branches of the subject, namely, abstract or theoretical, and concrete or applied, entirely different modes of inquiry are appropriate. The essential principles of moral obligation, if any such can be said to exist, are, presumably, like the truths of pure mathematics, self-evident; and unless we are prepared to take them blindly on authority, the appropriate method of reaching them appears to be introspection, self-interrogation. Suppose that I wish to decide whether the principle of doing as one would be done by is a genuine fundamental principle of morality, and binding upon us, or whether it goes needlessly far in the direction of self-sacrifice. If the question is to be answered to my satisfac-
