management of the head, as at every thump of the thumbs against the temporal bones a dull sound was heard. The objectivity of the fingers was found out not much before this time by involuntary, painful biting of them, for as late as the fifteenth month the child bit his finger so that he cried out with pain. Pain is the most efficient teacher in the learning of the difference between subjective and objective. Another important factor is the _perception of a change produced by ones own activity_ in all sorts of familiar objects that can be taken hold of in the neighborhood; and the most remarkable day, from a psychogenetic point of view, in any case an extremely significant day in the life of the infant, is the one in which he first experiences the _connection of a movement executed by himself with a sense-impression following upon it_. The noise that comes from the tearing and crumpling of paper is as yet unknown to the child. He discovers (in the fifth month) the fact that he himself in tearing paper into smaller and smaller pieces has again and again the new sound-sensation, and he repeats the experiment day by day and with a strain of exertion until this connection has lost the charm of novelty. At present there is not, indeed, as yet any clear insight into the nexus of cause; but the child has now had the experience that he can himself be the cause of a combined perception of sight and sound regularly, to the extent that when he tears paper there appears, on the one hand, the lessening in size; on the other hand, the noise. The patience with which this occupation--from the forty-fifth to the fifty-fifth week especially--is continued with pleasure is explained by the gratification at being a cause, at the perception that so striking a transformation as that of the newspaper into fragments has been effected by means of his own activity. Other occupations of this sort, which are taken up again and again with a persistency incomprehensible to an adult, are the shaking of a bunch of keys, the opening and closing of a box or purse (thirteenth month); the pulling out and emptying, and then the filling and pushing in, of a table-drawer; the heaping up and the strewing about of garden-mold or gravel; the turning of the leaves of a book (thirteenth to nineteenth month); digging and scraping in the sand; the carrying of footstools hither and thither; the placing of shells, stones, or buttons in rows (twenty-first month); pouring water into and out of bottles, cups, watering-pots (thirty-first to thirty-third months); and, in the case of my boy, the throwing of stones into the water. A little girl in the eleventh month found her chief pleasure in "rummaging" with trifles in drawers and little boxes. Her sister "played" with all sorts of things, taking an interest in dolls and pictures in the tenth month (Frau von Struempell). Here, too, the eagerness and seriousness with which such apparently aimless movements are performed is remarkable.