One more comment: I recently finished a book called Psychotherapy With "Impossible" Cases. Do mental health people use the term "impossible"? Yes, they do. Why otherwise would these people write a book with such a title?

"Impossible" means something cannot be done. The impossibility lies in objective reality, not in the particular circumstances of client A with therapy B. People use words carelessly, and that kind of use can have consequences. It can kill.

off.