_Fear the conservative instinct under its defensive form—Physiology—Psychology—First stage: Instinctive fear—Hypothesis of heredity—Second stage: Fear founded on experience—Pathology—Morbid or pathological fears—Two periods in their study—Attempts at classification—How are they derived from normal fear? Two groups, connected respectively with fear and disgust—Inquiry into the immediate causes: events in life of which a recollection has been retained; of which no recollection has been retained—Occasional transformation of a vague state into a precise form._ The instinct of individual conservation, under its defensive form, is the origin of the emotion called fear, and its varieties. We have already said, more than once, that it is the first in chronological order of appearance, showing itself, according to Preyer, at twenty-three days; according to Perez, at two months; while Darwin puts it as late as the fourth month. It is the first manifestation in the consciousness of emotion properly so called, as a psycho-physiological complexus. Following the method which will be invariably applied to every emotion, simple or composite, we shall examine in turn its psychology and its pathology. I. It has been defined as “the particular emotive reaction which takes place through a sufficiently vivid and persistent representation of possible pain or evil.”[132] This formula, though good in the majority of cases, does not seem applicable to the first stage of fear, as we shall see presently. Footnote 132: J. Sully, _The Human Mind_, vol. ii. p. 91. The reader should also consult Mosso’s well-known monograph on _Fear_ (English tr.), and Bain, _The Emotions_, ch. viii. Fear has been tolerably well studied. The absence of monographs concerned with the other emotions is another proof that emotional psychology is yet in its infancy, whereas for the memory, perceptions, images, etc., we find, on the contrary, a large number of special studies on special points. The physiology of fear has been worked out by Darwin, Mantegazza, Mosso, and Lange. I prefer the last writer’s description, as being more systematic; it is not a collection of isolated facts, but a logically arranged synopsis. We know already the importance attached by him to the physiological conditions of each emotion. The characteristic marks of fear are:— 1. As regards the innervation of the voluntary muscles: a greater weakening than in the case of sorrow, a convulsive tremor; in extreme cases, suppression of all movement, one is fixed to the spot; voice hoarse and broken, or complete dumbness; in short, a more or less accentuated paralysis of the whole voluntary motor apparatus.