So far, we have shown that there is an unconscious part of the mind which acts as a store-house for memories, ideas, and emotions of the past. We have not, however, shown that it is anything more than a store-house. But if we look into it from other points of view, we shall see that it is a great deal more than a mere store-house, for it thinks, reasons, comes to conclusions, and in fact assists in controlling our acts at every turn; indeed this unconscious part of our mind wields driving forces of the utmost potency in moulding our lives. Let us examine first the _reasoning_ faculty of the unconscious mind. Maeder gives a good example of this. A house-surgeon at a hospital wished particularly to keep a certain appointment, but he was not allowed to leave the hospital until his chief, who was out, should return later in the evening. As his appointment was of considerable importance, he decided to brave the anger of his chief. He therefore kept his appointment, but when he returned later, he found to his astonishment that he had left a light in his room, a thing he had never done before, although he had occupied that room for two years. He thought the matter over, and soon realised why he had done this. The chief, on going to his own house, would pass the window and would see the light burning within, and imagine that his house-surgeon was at home. The unconscious mind had rapidly reasoned this out and had determined that the conscious mind should forget to turn off the light.