We must not suppose, however, that the man who is experiencing some or all of these mental and bodily conditions is at this period necessarily displaying any obvious _outward_ signs of his trouble. There may be no tremor, no twitchings, no loss of control of the facial or vocal muscles which would indicate his state even to his neighbours. He may, for a long time, “consume his own smoke.” And during this process he may even appear to his comrades to be steadier and more contemptuous of danger than before. Dr. Forsyth[9] has cited some dramatic incidents, in which officers who imagined that their instinctive fear was becoming apparent to the men under their command took unnecessary risks in order to impress these men with the idea that they were not afraid. It must be understood that this suppression of the external manifestations of an emotion such as fear is but a partial dominance of the bodily concomitants of that emotion. The only changes which can usually be controlled by the will are those of the voluntary or skeletal muscular system, not those of the involuntary or visceral mechanism. While no signs of fear can yet be detected in the face, the body, limbs or voice, these disturbances of the respiratory, circulatory, digestive and excretory systems may be present in a very unpleasant degree, probably even intensified because the nervous energy is denied other channels of outlet.[10] The suppression of fear and other strong emotions is not demanded only of men in the trenches. It is constantly expected in ordinary society. But the experience of the war has brought two facts prominently before us. First, before this epoch of trench warfare very few people have been called upon to suppress fear continually for a very long period of time. Secondly, men feel fear in different ways and in very various degrees. The first fact accounts for the collapse, under the long continued strain of trench warfare, of men who have shown themselves repeatedly to be brave and trustworthy. They may have felt intense emotions, obviously not of fear alone, for a long time without displaying any signs of them. But suppression of emotion is a very exhausting process. As Bacon says, “We know diseases of stoppings and suffocations are the most dangerous in the body; and it is not much otherwise in the mind.” The second fact mentioned above is of great importance in the consideration of our problem. There are undoubtedly men who seem to be immune to fear of the dangers of warfare. But to them we can scarcely apply the adjective “brave.” The brave man is one, who, feeling fear, either overcomes it or refuses to allow its effects to prevent the execution of his duty.