mental soundness
mental balance

Carefully she felt for mental balance, achieved it, and waited.

He had the impression that she was weighing him in some sort of mental balance.

With the first bump, at the age of 10, he loses his mental balance.

Their superb physical and mental balance was the most obvious feature about them.

Durotige did not lose his mental balance for more than a second or two.

You behave like a man who has lost his mental balance!

"An argument for mental balance if I ever heard one."

I merely helped your mother maintain a healthy mental balance.

Things had happened so fast since last night that she'd never had time to get her mental balance.

Then he continued his investigations which helped to restore mental balance.