With this degree of certainty we must perforce content ourselves, in dealing with outside nature. In trying to understand and interpret that which is not ourselves, we hit upon barriers which cannot be transcended, upon a foreign factor which opposes itself to our endeavors. But it is otherwise in the sphere of conduct. Here, if there is to be certainty at all, in regard to right as distinguished from wrong, if there is to be such a thing as right in the strict sense, we cannot content ourselves with the paradoxical, relative-absolute just described. For here we not merely interpret but act, and we must possess an ideal plan of the whole if we are to be certain of our rightness in any particular part of conduct. _For in conduct there is no such partial coincidence between the rational and the irrational as in the case of physical law._ There is not a single partial rule of conduct, neither “Thou shalt not kill” nor “Thou shalt not lie,” nor any other that, taken by itself, is of itself ethically right. It may be right, it may be wrong. It takes its ethical quality from the plan of conduct as a whole, and without reference to the whole it is devoid of rightness.[25] I have thus indicated the ground of the distinction between the method of science and the method of ethics, a distinction, it is true, to which Kant himself did not adhere. Partial coincidence of the rational with the irrational is expressed in physical law; absence of such concurrence destroys any attempt to build up an ethical theory on the empirical method. We cannot plant our feet on the part, gaining there the sense of certainty: we must creatively conceive the ideal of the whole and educe every partial mode of ethical conduct from that. But how shall we proceed in the construction of such an ideal, for it is obvious that knowledge, in the scientific sense of the word, is entirely out of the question? FOOTNOTES: [23] See the more extended remarks on this subject in Book III. [24] In Kant’s view the rational element is projected on the irrational. In this way spatial juxtaposition is ideally transformed into a spatial continuum. In the same manner temporal sequence is ideally changed into a uniform temporal flux. Without the former, geometry could not have established its propositions; without the latter Galileo could not have measured the fall of the stone. [25] The ethical character of acts depends on the worth of the agent and the object. Is it right to kill or to enslave a fellowman? We do not hesitate to kill an animal, or to harness horses to vehicles, or to use them as beasts of burden. Why not kill men, or use them as beasts of burden in like manner?—Only because they possess a worth which gives them a different standing.