If a sign produces any further proper significate effect, it will do so through the mediation of the emotional interpretant, and such further effect will always involve an effort. I call it the energetic interpretant. The effort may be a muscular one, as it is in the case of the command to ground arms; but it is much more usually an exertion upon the Inner World, a mental effort. It never can be the meaning of an intellectual concept, since it is a single act, [while] such a concept is of a general nature.
…many signs bring about actual events. The infantry officer’s word of command “Ground arms!” produces as its existential interpretant, (the sign having first been apprehended in an “emotional interpretant,”) the slamming down of the musket-butts. The less thought intervenes between the apprehension and this act, the better the sign fulfills its function. All signs that are not to evaporate in mere feelings must have such an existential interpretant, or as I might better have called it, such an energetic interpretant. [—] The existential, or energetic, interpretant […] corresponds to the real object whose action is obscurely […] the active cause of the sign.
It is now necessary to point out that there are three kinds of interpretants. Our categories suggest them, and the suggestion is confirmed by careful examination. I terms them the Emotional, the Energetic, and Logical Interpretants. They consist respectively in feelings, in efforts, and in habit-changes. [—]
The majority of signs, in their significative capacity, provoke efforts, whether they be efforts in the outer or the inner world, or whether they be efforts of inhibition, or self-restraint, which make so large a part of the effort to pay attention. An event may provoke an effort of the mind, and not a mere reflex response of the body, without being thereby a sign; but if one becomes definitely conscious, in the provoked effort, of acting against a resistance, or of resisting a force, then the notion of such resistance or such active force is conveyed; and there is a sign.