This probably gives a true hint of the history of emotional development in the race: for in the animal world, too, fear appears earliest of all the emotions, and in the simplest forms of fright is hardly to be distinguished from mere reflex action; and it is caused oftener by sound than by anything else. When we remember the theory that hearing is developed from the more ancient motion sense, we are tempted to trace the origin of fright still farther back, to the very primitive reflex sensibility to jarring movement, of which I have spoken before. And now the baby had come to six weeks old, and could hold up her head perfectly for a quarter of a minute at a time, and liked greatly to be held erect or in sitting position. Apparently all this was for the sake of seeing better, for her joys still centred in her eyes. She had made no advance in visual power, however, except that within a few days she could follow with her eyes the motion of a person passing near her. Human faces were still the most entertaining of all objects. She gazed at them with her utmost look of intentness, making movements with her hands, and panting in short, audible breaths. Nothing else had ever excited her so, except once a spot of sunlight on her white bed. There were signs that her experiences gathered more and more into groups in her mind, by association. I have spoken of her earlier association between the nursing position and being fed; now she would check her hungry crying as soon as she felt herself lifted; and a few days later, as soon as her mouth was washed out--a ceremony that invariably came before nursing. At seven weeks old she opened her mouth for the nipple on being laid in the proper position. The food association group was enlarging; but sight did not yet enter into it: the look of the breast did not seem to bring the faintest suggestion of satisfied hunger, and the baby would lie and cry with her lips an inch from it. This is natural, for she could never really have seen it at this stage of the development of vision. I have said that in such associations there is a germ of memory. There is a sort of habit memory, too, that appears very early. Impressions that have been received over and over gather a sort of familiarity in the baby’s mind; and while he does not yet recognize the familiar things themselves, yet he feels a change from them as something strange--it jars somehow the even current of his feelings. Or where impressions have been especially agreeable, they are vaguely missed when they are absent. The consciousness of difference between society and solitude, which our baby had showed at the end of the first month, was habit memory of this sort.