As children become physically differentiated in respect of sex, so also does a mental differentiation ensue. Authorities are not agreed as to whether mental sexual differentiation exists in the very earliest years of life. Many assume its existence, and profess to have observed sexual differences even in the movements of quite small children. On the other hand, it is urged that the alleged differences are made up out of chance, auto-suggestion on the part of the observer, and the results of education. There is, however, general agreement as to the fact that during the second period of childhood mental differences become apparent between the sexes. Such differences are observed in the matter of occupation, of games, of movements, and numerous other details. Since man is to play the active part in life, boys rejoice especially in rough outdoor games. Girls, on the other hand, prefer such games as correspond to their future occupations. Hence their inclination to mother smaller children, and to play with dolls. Watch how a little girl takes care of her doll, washes it, dresses and undresses it. When only six or seven years of age, she is often an excellent nurse. As Padberg[15] pictures her, she sits at the bedside of her sick brother or sister, resembling as she does so an angel in human form. Her need to occupy herself in such activities is often so great, that she pretends that her doll is ill. Chamisso, in his poem _Das kleine Maedchen und die Puppe_ (_The Little Girl and her Doll_), describes this relationship between the child and her doll, one whose nature is fully understood only by a mother:-- "Wie Du mit den kleinen Kindern, Will ich alles mit ihr tun, Und sie soll in ihrer Wiege Neben meinem Bette ruhn. Schlaeft sie, werd' ich von ihr traeumen, Schreit sie auf, erwach' ich gleich,-- Mein himmlisch gute Mutter, O, wie bin ich dock so reich!" "All you do for your children, For my Doll I do instead, And in her little cradle She lies beside my bed. When she sleeps, I dream about her, When she cries, I wake up too. My own, dear, darling Mother, I'm just as rich as you!"