the force and directness of their aim. They are trying the power of will over matter.”[231] This is the correct designation of the peculiar satisfaction derived from throwing. It is that which comes from sending the object from us and, as it were, projecting our individuality into a wider sphere of action. Souriau says: “We take a special interest in the extension of motion originated by ourselves. It becomes a part of us. The force which we behold at work outside of us is our own.”[232] If we include rolling or sliding in our definition of throwing, we are confronted by a bewildering variety of games;[233] but since the ends of a general psychology of play would not be furthered by an enumeration of these, we will try to single out such as illustrate the varied forms of satisfaction which throwing in general affords. First of all let us keep in mind our principle, that inventive play presupposes a complication of instinctive tendencies through the satisfaction of which enjoyment is greatly enhanced. Usually it is impulses for fighting and imitation which ally themselves with that toward movement and render the play more varied and pleasurable. There are, indeed, very few throwing plays that have not culminated in contests of one kind or another, and many are at the same time imitative, though whether they were originated by children or adults it is difficult or even impossible to say. Our study of primitive acoustic instruments showed that the child is sometimes actively inventive. Trying, then, to keep clear as much as possible of fighting and imitative play, we distinguish several kinds of throwing plays which we may briefly characterize as follows: (_a_) Simple throwing, upward, downward, or horizontally; (_b_) propulsion by means of a blow (_c_) rolling, spinning, shoving, and skipping; (_d_) throwing at a target. (_a_) Simple Throwing