"When someone goes to the doctor and says, "I hear a voice in my head," he or she will most likely be sent to a psychiatrist. The fact is that, in a very similar way, virtually everyone hears a voice, or several voices, in their head all the time: the involuntary thought processes that you don't realize you have the power to stop... The voice comments, speculates, judges, compares, complains, likes, dislikes, and so on. The voice isn't necessarily relevant to the situation you find yourself in at the time; it may be reviving the recent or distant past or rehearsing or imagining possible future situations. Here it often imagines things going wrong and negative outcomes; this is called worry. p. 16 ...When you listen to a thought, you are aware not only of the thought but also of yourself as the witness of the thought. A new dimension of consciousness has come in. p. 17"
January 1, 1970
https://en.wikiquote.org/wiki/Worry