It is also common knowledge that a great many events and scenes of considerable importance to us at the time of action are forgotten, and that they can only be recollected if some sort of stimulus or reminder be given. For instance, a person may have forgotten completely where and how he spent a holiday ten years ago. No amount of racking his brain brings anything to light. But having been reminded of a single incident that occurred during that holiday, the whole of the rest may come up from the unconscious in full detail. There is a third kind of memory more important still, if one may be permitted to call it memory, and that is the memory of facts which no _ordinary_ stimulus of this sort will ever bring up into consciousness again. The term “memory” is used here because we have every reason to believe that somewhere in the unconscious all facts have been registered, and in many cases may be partially brought into consciousness again by suitable means, such for instance, as hypnotism or psycho-analysis, (two very different methods, by the way). Yet, though these impressions have been made on the mind, and though there is this unconscious memory still in existence, in the ordinary course of events we should never again be conscious of them. _We may, however, be very conscious of actions and emotions emanating from the unconscious memory._ Thus, suppose that as a child one had lived in the country, and on several very happy occasions a bonfire had been lighted at a picnic, and that later on one lived in a town, and that this picnic which happened at the age of three or four years had become completely forgotten, so much so that even photographs of the scenes or conversations on the subject carried on by other people brought no memory to light and seemed to touch no chord; it would still be quite likely that the mere smell of a bon-fire in the distance or any smell resembling this would be enough to cause a considerable feeling of elation and happiness in the person, a feeling that something pleasant was taking place, an idea that if only one could remember, a pleasant picture could be called up. This is because it is associated in the unconscious mind with these previous happy occasions.