From Wikipedia:
In 1913, at the age of thirty-eight, Jung experienced a horrible “confrontation with the unconscious”. He saw visions and heard voices. He worried at times that he was “menaced by a psychosis” or was “doing a schizophrenia”. He decided that it was valuable experience and, in private, he induced hallucinations or, in his words, “active imaginations”.
Quite interesting
It’s true. He documented his experiences with psychosis in his Red Book.
He also developed the theory of Synchronicity.
Also Sigmund Freud used cocaine to help his depression.
As the founder of one of the most influential schools of psychological thought — analytical psychology — Carl Jung (also known as CG Jung) experienced what today we might call a form of psychosis. It probably wasn’t a complete psychotic break, because Jung still functioned in his daily life.
I think it’s more likely he experienced what nowadays would be called ‘subclinical psychotic symptoms’,