The definition of evil in mechanistic terms is now within our reach. We have said before that “evil” is an intensification of the term “bad,” which latter term was used to describe an incoordinate condition of the organism brought about because its wishes, interests, and purposes,—in a word, its action-patterns,—had been thwarted. Just what more than this does “evil” imply? _It implies that our wishes have been thwarted to such an extent as to call forth from us the most energetic, antagonistic reactions of which we are capable._ “Good” signifies an outgoing reaction, “bad” signifies a withdrawing reaction, while “evil” means that within the organism some of the available energies are being hastily mobilized to compensate for an outgoing reaction that has been thwarted. Of course, there are many persons who never attempt any compensation of such a constructive character as to prevent the recurrence of the same evil situation, either because they are physically unfit, or are poor in spirit, but in such cases the word “evil” is used without very much meaning. Our definition of this concept will, I think, serve to provide a new interpretation of the statement made previously, namely, that “evil always carries with it the presumption of standards or rules.” What, precisely, does this statement mean? It means that whenever we have lost our organic equilibrium in the presence of a situation described as _evil_, whatever we do to recover it _ipso facto_ at that moment defines not only the standard and rule by which our conduct is regulated, but such behavior also reveals to others just what the “problem of evil” really means to us. For example, if we are vexed and become profane, profanity is patently an integral factor in our philosophy of compensation. If we lose our money, and steal another’s to make good our loss, theft is a cardinal principle in our doctrine of equalization. We may, to be sure, immediately thereafter lament the outburst by which we attempted to “set things to rights,” but we cannot retrieve the action by which we defined and exhibited our practical ethical philosophy. Our recent Emerson had this scientific truth in mind when he said, “What you are speaks so loud, I cannot hear what you say.” Examples of another sort are equally illuminating. If Socrates is condemned to death for corrupting the Athenian youth, and calmly drinks the hemlock in order to remain a law-abiding citizen to the end, this deed of probity defines the dominant action-pattern in his philosophy of retaliation. If Jesus is crucified for blasphemy and inciting to insurrection, and manifests an attitude of non-resistance and equanimity, these action-patterns once more exhibit his method of dealing with the problem of evil. In every such case the bodily habits which have long accumulated are automatically released by the appropriate stimulus into overt behavior. In physiological terms, what a man does in