There is another class of movements, often confused with the reflex--that is, instinctive movements. Real grasping (as distinguished from reflex grasping), biting, standing, walking, are examples of this class. They are race movements, the habits of the species to which the animal belongs, and every normal member of the species is bound to come to them; yet they are not so fixed in the bodily mechanism as the reflex movements. The stimulus to them seems to come more from within than from without--yet not from reason and will, but from some blind impulse. This impulse is usually imperfect, and the child has to work his own way to the mastery of the movements. Yet though certain reflex activities are inherited in a more highly developed condition than any human instincts, the instincts are at bottom _always_ hereditary, which is not the case with the reflexes--any one may teach his muscles new reflex movements, unknown to his ancestors. A musician does it every time that he practices new music till his hands will run it off of their own accord, while he is thinking of something else. But instinct cannot be thus acquired. The amazing instincts of the lower animals; the imperfect and broken condition of the instincts in man, yet the deep hold that they have on him; the mingling of inherited necessity and individual freedom in the way in which they are worked out; the mystery of the physiological method by which they act (while that of reflex movement is fairly well understood, up to a certain point); the light they seem always about to shed for the biologist on the profoundest problems of heredity, and for the philosopher on those of free will and personality,--these things make instinct one of the great fields of present research, and I must not venture into it, though it is of importance in trying to understand a baby. I shall say only that while instinct does not appear in the lowest animals (whose action is all of the reflex type), and is for a time a sign of rising rank in the scale of life, it reaches its culmination with the insects, and as we approach man it is the breaking up of the instincts that is in its turn a sign of advancement to higher life. The little chicken runs about as soon as it is out of its shell, and even the monkey baby is able to take care of itself in a few months. Nothing is so helpless as the human baby, and in that helplessness is our glory, for it means that the activities of the race (as John Fiske has so clearly shown) have become too many, too complex, too infrequently repeated, to become fixed in the nervous structure before birth; hence the long period after birth before the child comes to full human powers. It is a maxim of biology (as well as the frequent lesson of common observation) that while an organism is thus immature and plastic, it may learn, it may change, it may rise to higher development; and thus to infancy we owe the rank of the human race.