Any one who has had much to do with children will realise that, if wrongly handled, they are apt to take a positive delight in doing what they conceive to be wrong. There is clearly a delightful element of excitement in the process of being naughty, of daring and of braving the wrath to come, with which they are so familiar and for which they care nothing at all. But the perverseness of which we are now speaking has a different origin. It arises only when children are reproved, appealed to, and expostulated with too often and too constantly. Negativism is a symptom which is common enough in certain mental disorders. The unhappy patient always does the opposite of what is desired or expected of him. If he be asked to stand up he will endeavour to remain seated, or if asked to sit he will attempt to rise to his feet. Like many other symptoms of nervous disturbance which we shall study later, this negativistic spirit is often displayed to perfection by little children when the environment is at fault and when grown-up people have too freely exercised authority. A mother, anxious to induce her little son to come to the doctor, and knowing well that her call to him to enter the room, as he stands hesitating at the door, will at once determine his retreat to the nursery, has been heard to say, "Run away, darling, we don't want _you_ here," with the expected result that the docile child immediately comes forward. To the doctor, that such a device should be practised almost as a matter of course and that its success should be so confidently anticipated, should give food for thought. It may shed light on much that is to follow later in the interview.