The impulse to opposition is a quality which is usually regarded as a very unpleasant disposition of mind, but which is in reality, when kept within proper bounds, the very leaven of human life. We shall see later that rivalry taken in connection with the imitative impulse is one of the mainsprings of advance of culture, and the oppositional force connected with the fighting instinct is also necessary for the mental development of mankind. The great newcomers in the various departments of learning are almost invariably either friendly or bitter opponents of long standing authorities, and any project which meets with no opposition sinks to sleep. For the individual, too, it is quite as important, since a man without it would be entirely too hospitable to suggestion; indeed, abnormal suggestibility rests finally on the suspension of this instinct. Children early show a playful as well as an earnest resistance to authority. While Sully is right when he says that an attitude of absolute hostility to law on the part of the child would make education impossible, still he admits that the best children—from a biological standpoint—have “most of the rebel” in them.[380] The sweetness of forbidden fruit is imparted largely by the combative instinct. Such a spirit is manifested playfully, not when disobedience is attended with cries and struggles or sulky behaviour, but when it is enjoyed for its own sake, as a source of triumphant satisfaction. When a two-year-old child who has been told not to throw his spoon under the table repeats the action, not in anger but with twinkling eyes, he is acting playfully. Some of their speeches, however, exhibit this spirit most clearly. For instance, a small boy who had been rather rough with his younger brother and was remonstrated with by his mother, asked, “Is he not my own brother?” and then cried triumphantly, when his mother admitted the undeniable fact, “Well, then, you said I could do what I please with my own things!”[381] Another child of three years and nine months answered his nurse who called him: “I can’t come; I have to look for a flea!” and pretended to be doing so while he broke out in a roguish laugh.[382] A three-year-old Italian girl said to her grandmother under similar circumstances, “Non posso venire, la piccolina [her doll] mi succhia!”[383]