The notion that animals consciously train and educate their young has been held only tentatively by European writers on natural history. Darwin does not seem to have been of this opinion at all. Wallace shared it at one time in regard to the birds,--their songs and nest-building,--but abandoned it later, and fell back upon instinct or inherited habit. Some of the German writers, such as Brehm, Büchner, and the Müllers, seem to have held to the notion more decidedly. But Professor Groos had not yet opened their eyes to the significance of the play of animals. The writers mentioned undoubtedly read the instinctive play of animals as an attempt on the part of the parents to teach their young. That the examples of the parents in many ways stimulate the imitative instincts of the young is quite certain, but that the parents in any sense aim at instruction is an idea no longer held by writers on animal psychology. Of course it all depends upon what we mean by teaching. Do we mean the communication of knowledge, or the communication of emotion? It seems to me that by teaching we mean the former. Man alone communicates knowledge; the lower animals communicate feeling or emotion. Hence their communications always refer to the present, never to the past or to the future. That birds and beasts do communicate with each other, who can doubt? But that they impart knowledge, that they have any knowledge to impart, in the strict meaning of the word, any store of ideas or mental concepts--that is quite another matter. Teaching implies such store of ideas and power to impart them. The subconscious self rules in the animal; the conscious self rules in man, and the conscious self alone can teach or communicate knowledge. It seems to me that the cases of the deer and the antelope, referred to by President Roosevelt in the letter to me quoted in the last chapter, show the communication of emotion only. Teaching implies reflection and judgment; it implies a thought of, and solicitude for, the future. "The young will need this knowledge," says the human parent, "and so we will impart it to them now." But the animal parent has consciously no knowledge to impart, only fear or suspicion. One may affirm almost anything of trained dogs and of dogs generally. I can well believe that the setter bitch spoken of by the President punished her pup when it flushed a bird,--she had been punished herself for the same offense,--but that the act was expressive of anything more than her present anger, that she was in any sense trying to train and instruct her pup, there is no proof.