a problem which means almost nothing, which presents a blank wall when he tries to attend to it, which offers no suggestions for solution, is an illustration of the first. Attention to such a problem is impossible; his attention must wander. The genius who, working with his favorite subject, finds a multitude of trains of thought called up by each idea, and who therefore spends hours on one topic with no vacillation of attention, is an illustration of the second. Attention has been classified according to the kind of feeling which accompanies the activity. Sometimes attention comes spontaneously, freely, and the emotional tone is that accompanying successful activity. On the other hand, sometimes it has to be forced and is accompanied by feelings of strain and annoyance. The first type is called Free[2] attention; the second is Forced attention. Free attention is given when the object of attention satisfies a need; when the situation attended to provides the necessary material for some self-activity. The activity of the individual at that second needs something that the situation in question gives, and hence free, spontaneous attention results. Forced attention is given when there is a lack of just such feeling of need in connection with the object of attention. It does not satisfy the individual--it is distinct from his desires at the time. He attends only because of fear of the results if he does not, and hence the condition is one of strain. All play takes free attention. Work which holds the worker because it is satisfying also takes free attention. Work which has in it the element of drudgery needs forced attention. The girl making clothes for her doll, the boy building his shack in the woods, the inventor working over his machine, the student absorbed in his history lesson,--all these are freely attending to the thing in hand. The girl running her seam and hating it, the, boy building the chicken coop while wishing to be at the ball game, the inventor working over his machine when his thoughts and desires are with his sick wife, the student trying to study his history when the debate in the civics club is filling his mind,--these are cases when forced attention would probably be necessary. It is very evident that there is no one situation which will necessarily take either free or forced attention because the determining factor is not in the situation _per se_, but in the relation it bears to the mind engaged with it. Sometimes the same object will call forth forced attention from one person and free from another. Further, the same object may at one time demand free attention and at another time forced attention from the same person, depending on the operation of other factors. It is also true that attention which was at first forced may change into free as the activity is persevered in.