The characteristic feature of a really dangerous national struggle for existence is the intensity of the stimulus it applies to the social instinct. It is not that it arouses “dormant” or decayed instincts, but simply that it applies maximal stimulation to instinctive mechanisms which are more or less constantly in action in normal times. In most of his reactions as a gregarious animal in times of peace, man is acting as a member of one or another class upon which the stimulus acts. War acts upon him as a member of the greater herd, the nation, or, in other words, the true major unit. As I have repeatedly pointed out, the cardinal mental characteristic of the gregarious animal is his sensitiveness to his fellow-members of the herd. Without them his personality is, so to say, incomplete; only in relation to them can he attain satisfaction and personal stability. Corresponding with his dependence on them is his openness towards them, his specific accessibility to stimuli coming from the herd. A threat directed towards the whole herd is the intensest stimulus to these potentialities, and the individual reacts towards it in the most vigorous way.[O] The first response is a thrill of alarm which {143} passes through the herd from one member to another with magic rapidity. It puts him on the alert, sets him looking for guidance, prepares him to receive commands, but above all draws him to the herd in the first instinctive concentration against the enemy. In the presence of this stimulus even such partial and temporary isolation as was possible without it becomes intolerable. The physical presence of the herd, the actual contact and recognition of its members, becomes indispensable. This is no mere functionless desire, for re-embodiment in the herd at once fortifies courage and fills the individual with moral power, enthusiasm, and fortitude. The meaning that mere physical contact with his fellows still has for man is conclusively shown in the use that has been made of attacks in close formation in the German armies. It is perfectly clear that a densely crowded formation has psychological advantages in the face of danger, which enable quite ordinary beings to perform what are in fact prodigies of valour. Even undisciplined civil mobs have, on occasion, proved wonderfully valorous, though their absence of unity often causes their enterprise to alternate with panic. A disciplined mob—if one may use that word merely as a physical expression, without any derogatory meaning—has been shown in this war on innumerable occasions to be capable of facing dangers the facing of which by isolated individuals would be feats of fabulous bravery. {144}