The list of instincts given on pp. 205 ff. includes tendencies of very different kinds, simple and complex, variable and constant. Sweeping statements are therefore dangerous; we must be careful to guard our generalisations by giving instances. That premised, we note, to begin with, that _the innate tendencies are rarely perfect_, completely ready for action, at birth; they ripen as the organism developes. The child does not learn to walk, or the bird to fly, in any strict sense of the word ‘learn’; the innate tendencies settle to their perfect work as time goes on. We note, secondly, that the tendencies may _ripen at very different levels of individual development_; the culmination of sex-interest at adolescence, the appearance of bashfulness in the child of three or four years, the lack of fear in the new-born babe, are cases in point. Thirdly, they are extraordinarily _persistent_. Our instincts, no doubt, wax and wane; but they change far less than their outward expression would indicate. The boy, we say, goes through the collecting stage, and therewith an end; but do not grown men too collect, if they have time and money? The little girl with her doll is the later mother with her child; and the play of the child persists in the technical play of the gambler and the experimental essays of the man of science. Fourthly, they are _by no means harmonious among themselves_. In many animals the instinct to crouch motionless conflicts with the instinct to flee from the object of fear, and you may see them obeying now the one and now the other. Curiosity conflicts with alarm: watch a young child on its first introduction to a dog or a beetle! The sparrow is at once audacious and cautious, bold and timid; and every human adult—despite the song in _Iolanthe_—is both conservative and radical. Fifthly, they are looser, have (so to say) _a greater freedom of play_, than is commonly supposed; and this in two directions; the same response may be touched off by situations that have only a general resemblance; and, conversely, situations that seem to be identical may touch off responses that show a good deal of difference. In briefer statement, like stimuli may call out the same response: we smile from happiness or from superiority; and the same stimulus repeated may call out responses that are hardly even like: the extreme case is, perhaps, our crying or laughing for joy. Sixthly, they are _liable to be checked, turned aside, inhibited, by acquired nervous tendencies_; habit is not only second nature, but may also overcome nature. A chick pecks at an humble-bee, and pays the penalty; thereafter it rejects yolk of egg. A pike in an aquarium, separated from minnows by a glass screen, struck repeatedly at its natural prey and bumped its head; when the screen was removed, the minnows were left undisturbed. If a sheet of glass is placed before the eyes, and a rubber-tipped hammer springs up and hits it, you wink,