And this suggests another source of puzzles of adolescence. In the alternating moods of excessive exertion and indolence there is the possibility of girls and boys learning the value of alternation of work and play and rest. But there is also the danger of acquiring the habit of resting all the time, and leaving not only the work for others, but also the activity of play. It is much better for children to rest because they are tired than because they are lazy. And, while it is true that the instincts are all for activity, it is easy enough for the growing individual to acquire the habit of passive absorption of whatever amusement is provided. It is better, then, for the young people to get their entertainment out of theatricals than out of the theatre, out of playing games than out of watching games, out of having adventures in the woods and in the water than out of reading about them. And, in every way, the most reliable safety-valve of the period is constant activity, as this is the best outlet for the many and conflicting emotions which are the source of the chief difficulties. When Arthur shows signs of getting restless it is a great comfort to be able to send him off on some errand, or to give him a definite task to do. But it is also a great service to the boy, for while he is at the work there is being used up the nervous energy that would otherwise appear at the surface as another "spell." And this principle is just as true for girls as it is for boys. Only you cannot send the girl to a piece of work requiring great bodily exertion--nor does she need this so much. Work is not only a satisfactory safety-valve for the emotions in general, but it is especially valuable as a means of diverting the thoughts and feelings from the growing consciousness of sex.