Aaron T. Beck M.D. working as a psychiatrist in the early 1960s was using psychoanalysis as his primary tool of psychotherapy when he began to "suspect that my patients were not reporting certain kinds of ideation. This omission was not due to any resistance or defensiveness on the part of the patient, but rather it had to do with the fact that the patient had not been trained to focus on certain kinds of thought. In retrospect, it is apparent to me that the types of ideation that had gone unnoticed are in fact crucial to understanding the nature of psychological problems. Although other psychoanalysts may have exposed this rich vein of material, they had not reported it as such in the literature. The following experience triggered my interest and consequent investigation of this un-verbalized material.

A patient in the course of free association had been criticizing me angrily. After a pause, I asked him what he was feeling. He responded, 'I feel very guilty.' At the time, I was satisfied that I understood the sequence of psychological events. According to the conventional psychoanalytic model, there was a simple cause-and-effect relation between his hostility and guilt; that is, his hostility led directly to guilty feeling. There was no need, according to the theoretical scheme, to interpose any other links in the chain.

But then the patient volunteered the information that while he had been expressing anger laden criticisms of me, he had also had continual thoughts of a self-critical nature. He described two streams of thought occurring at about the same time: one stream having to do with his hostility and criticisms, which he had expressed in free association, and another that he had not expressed. He then reported the other stream of thoughts: 'I said the wrong thing... I shouldn't have said that ... I'm wrong to criticize him ... I'm bad ... He won't like me ... I'm bad ... I have no excuse for being so mean.'

This case presented me with my first clear-cut example of a train of thought running parallel to the reported thought content. I realized that there was a series of thoughts that linked the patient's expression of anger to guilty feelings. Not only was the intermediate ideation identifiable, but it directly accounted for the guilty feeling: The patient felt guilty because he had been criticizing himself for his expressions of anger to me."

In the forty or so years since then, Dr. Beck and his associates and students and indeed thousands of therapists around the world have brought Cognitive Therapy and it's child variations into a model of personality and system of psychotherapy that is powerful and important.