Is the cause of madness always knowable? Must one have access to the brain to find the deformity or defect? The value of autopsies is to allow us to uncover a cause. Without it we can only guess.
Is all madness detectable and provable? Are some forms elusive? Do the insane go in and out of reality or are they stuck in a world of their own making?
You are colorblind and see the world in shades of gray. You would never enjoy a rainbow or a sunset. All gray every day gray gray gray. And you think everyone sees the world in that exact same way but they don't.
And so it goes.