=A Chain of Associations.= Psycho-analysis is not, like hypnosis, based on dissociation; it is based on the association of ideas. Its main feature is a process of uncritical thinking called "free association." To understand it, one must realize how intricately woven together are the thoughts of a human being and how trivial are the bonds of association between these ideas. One person reminds us of another because his hair is the same color or because he handles his fork in the same way. Two words are associated because they sound alike. Two ideas are connected because they once occurred to us at the same time. A subtle odor or a stray breeze serves to remind us of some old experience. Connections that seem far-fetched to other people may be quite strong enough to bind together in our minds ideas and emotions which have once been associated, even unconsciously, in past experience. In this way, thoughts in consciousness and in the upper layers of the subconscious are connected by a series of associations, forming links in invisible chains that lead to the deepest, most repressed ideas. Even a dissociated complex has some connection with the rest of the mind, if we only have the patience to discover it. Therefore, by adopting a passive attitude, by simply letting his thoughts wander, by talking out to the physician everything that comes to his mind without criticizing or calling any thought irrelevant or far-fetched, and without rejecting any thought because of its painful character, the patient is helped to trace down and unearth the troublesome complex which may have been absolutely forgotten for many years. He is helped to relive the childhood experiences back of the over-strong habits which lasted into maturity.