"I consider it a sign of mental stability that I'm able to own things and not go crazy."

But John's mental stability is just one of her problems.

We don't concern ourselves with analyzing politics or mental stability.

There have been times when I've feared for his mental stability.

Similarly, officials can help determine the mental stability of their own soldiers.

"Don't think he has the mental stability that showed up on all our test scores."

So friends are supposed to prove each other's mental stability?

"But my mental stability and everything is what's important to me right now."

"After the exam, when did you first doubt your father's mental stability?"

The question of Robert's mental stability came up in several discussions.