What is sanity?

[Karla]

The labels "crazy" and "insane" are used sooo frequently to label people who do not conform to mainstream beliefs, even medicate and vindicate people.

How do we know what insanity is if we only base it off of how well it fits the current mainstream acceptable beliefs? 

What is crazy today might be sane next year-- how does anyone get away with terms like this with no ground? 

What is TRUE sanity/ non-crazy?