There is in the mind a mass of past experiences which cannot be readily remembered. We also know that while the individual is aware of some of the processes of elaboration going on in his mind, there are other mental processes which elude his observation. Both forgotten experiences and unrealized mental processes constitute material of which the individual was said to be “not personally conscious.” The modern psychologist says the forgotten memories and the hidden mental processes are in the unconscious or subconscious mind, a stratum of the mind below the threshold of personal consciousness. He bases this statement on the conception that while the mind is a complete entity, it is so disposed that while the contents of one portion can be at once investigated by the individual, the rest is not so easily explored. The accessible portion is called the conscious mind, the rest the unconscious. Dr. G. Stanley Hall compared the mind to an iceberg, floating in the ocean with one-ninth visible above the water and eight-ninths below, the visible ninth corresponding to the conscious mind, and the larger submerged portion to the unconscious mind. Before the time of Freud there was no satisfactory method of exploring the unconscious. Freud, when dealing with neurotic and mental patients, was dissatisfied with the results obtained by hypnotism. But he noticed that some experienced relief, and also improved, when encouraged to talk frankly about their anxieties and difficulties. He worked out a method of exploring the unconscious mind, called psycho-analysis, founded on the theory that dreams are not accidental or meaningless; interpreted by the method of free association, they constitute the royal road to the unconscious mind. Free association means that when the analysand is asked of what a particular item in the dream makes him think, he gives the idea that first occurs to him, however far-fetched or absurd it may seem, and then allows one idea to call up others without let or hindrance.