When Wilhelm was four years old there came a little sister, a bright, light-haired, blue-eyed creature after her father's heart. She was named Luise, but she was always called Blondchen. She was his only playfellow, as the irritable father in Moscow cared for no acquaintances. His father's one wish was to return to his home, but for a long time the mother would not have it so. At last, in the year 1858, he accomplished his wish. He was then sixty-three years old, and he represented to his wife that after his life of unremitting work, now in its undoubted decline, he had a right to spend the last few years in peace in his native land. He possessed enough for his family to live on; the children would grow and get a better education than in Russia, and above all he wished to keep his Prussian nationality. The mother yielded, and so they came to Berlin, where the father bought a modest house near the Friedrich-Wilhelm gymnasium. This house was now Wilhelm's property. "We children liked Berlin very much. I soon became independent and self-reliant, after school hours wandering in the streets as much as I pleased, and used to make eager explorations in all directions, coming home enraptured when I had found a beautiful neighborhood, a stately house, a statue of some general in bronze or marble. I used to take Blondchen by the hand, and show her my discovery. The Friedrichstadt with its straight streets interested us very much; I had a fancy that the houses were marshaled in battalions, as if by an officer on parade, and that when he gave the word 'March,' they would suddenly walk away in step, like the soldiers on the parade ground. I explained this to my sister, and often when we were in our own street she would call out 'March!' to see if the long row of houses would not begin to move. However, we liked the old part of Berlin better, where the streets, with their capricious and serpent-like windings, reminded us of the crooked alleys of Moscow. The streamlets of the Spree exercised a powerful attraction over us. Blondchen thought they played hide-and-seek with children, who would run through the streets to search for them. They came suddenly into sight where one would least expect to see them, in the yard of a house in the Werderschen Market, behind an apparently innocent archway on the Hausvogtei Platz, at the backs of houses whose fronts betrayed no existence of any water near. My sister so often longed to catch sight of the oily satiny sheen of the river's light in unsuspected places that she would drag me off to note her discoveries. She wanted all the varying sights of the Spree, which showed itself at the ends of alleys, or in courtyards or behind houses, suddenly to appear to her, so that she might have the right to first name her discovery."