If you look up the definition of sanity on the Internet it reads something like this:

1. The quality or condition of being sane; soundness of mind.
2. Soundness of judgment or reason.
3. The state or character of being sane; soundness of mind; saneness. See insanity.

Which doesn't help much, sanity is being sane.  OK, and water is wet.  So what is sane?

1. Of sound mind; mentally healthy.
2. Having or showing sound judgment; reasonable.
3. Being in a healthy condition; not deranged; acting rationally; -- said of the mind.

Which doesn't help much either.  OK, let's try "sound mind"

Well, there's a problem there "of sound mind" basically means sane.

Anybody recognizing circular logic?

The fact of the matter is we define sanity as reacting to a particular set of facts the way the rest of society expects you to.  If you do, you're sane, if you don't you are insane.

Of course society isn't necessarily sane, society's group reaction when wrong can destroy a civilization.

There's a point to this somewhere supposedly.  These guys:

Well are they sane? 

And that's the kind of characters I work with in my comics.  Entities that are a bit off, don't take the direct route to anything, but end up making correct decisions

Even the guy in the purple bunny suit ;)