I began to have a certain kind of experience when I was still a teenager, which I think can be best described as "the experience of detachment". Sometimes I had the experience almost every day; it felt very strange. I could find no better description of such experience than the following passage in James Joyce's short story "A Painful Case" (in Dubliners):
He lived at a little distance from his body, regarding his own acts with doubtful side glances. He had an odd autobiographical habit which led him to compose in his mind from time to time a short sentence about himself containing a subject in the third person and a predicate in the past tense…. Sometimes he caught himself listening to the sound of his own voice…. he heard the strange impersonal voice which he recognized as his own.
I still experience this, though less often now. When it first happened to me, I had no control of it; it suddenly took place, and suddenly disappeared. Over the years I have learned how to bring it about at will and how to stop it. I wonder how many people have similar experience.