4. All training of the one-year-old and of the two-year-old child must be, so far as possible, prevented. I have in this respect been so far successful that my child was not until late acquainted with such tricks as children are taught, and was not vexed with the learning by heart of songs, etc., which he was not capable of understanding. Still, as the record shows, not all unnecessary training could be avoided. The earlier a little child is constrained to perform ceremonious and other conventional actions, the meaning of which is unknown to him, so much the earlier does he lose the poetic naturalness which, at any rate, is but brief and never comes again; and so much the more difficult becomes the observation of his unadulterated mental development. 5. Every interruption of one's observation for more than a day demands the substitution of another observer, and, after taking up the work again, a verification of what has been perceived and noted down in the interval. 6. Three times, at least, every day the same child is to be observed, and everything incidentally noticed is to be put upon paper, no less than that which is methodically ascertained with reference to definite questions. In accordance with these directions, tested by myself, all my own observations in this book, and particularly those of this chapter, were conducted. Comparison with the statements of others can alone give them a general importance. What has been furnished by earlier observers in regard to children's learning to speak is, however, not extensive. I have collected some data in an appendix. CHAPTER XIX. DEVELOPMENT OF THE FEELING OF SELF, THE "I"-FEELING. Before the child is in a condition to recognize as belonging to him the parts of his body that he can feel and see, he must have had a great number of experiences, which are for the most part associated with _painful feelings_. How little is gained for the development of the notion of the "I" by means of the first movements of the hands, which the infant early carries to the mouth, and which must give him, when he sucks them, a different feeling from that given by sucking the finger of another person, or other suitable objects, appears from the fact that, e. g., my child for months tugged at his fingers as if he wanted to pull them off, and struck his own head with his hand by way of experiment. At the close of the first year he had a fancy for striking hard substances against his teeth, and made a regular play of gnashing the teeth. When on the four hundred and ninth day he stood up straight in bed, holding on to the railing of it with his hands, _he bit himself on his bare arm_, and that the upper arm, so that he immediately cried out with pain. The marks of the incisors were to be seen long afterward. The child did not a second time bite himself in the arm, but only bit his fingers, and inadvertently his tongue.