... which greatly confuses me (not the me being wrong part, though that sucks too)...

I can easily see how we can say "Yes, I believe he knew what he was doing at the time, so I think that counts as legally sane." I cannot easily see saying "a sane man could manage to convince himself that the massacre was not only good and necessary, but that he should bridge the gap between thought and action." Isn't that the definition of sociopathic behavior? Perhaps I have to brush up on my definitions.