Nature is trying very hard to make us succeed, but nature does not depend on us. We are not the only experiment.
And via Kit Whitfield, a piece of excellent advice:
Ask me today if a patient who's just emerged from surgery under general anaesthesia should be discharged five minutes after she comes around, especially if she's crying, and I'll tell you no, of course not; a hospital would be completely irresponsible to let her go. Yesterday, I completely lost track of that. It's an interesting lesson in perspective, in a spooky sort of way: never forget, you might be out of your mind.
Unfortunately, this assumes that you're still sufficiently together to recognise the fact that your thoughts no longer make sense, which isn't necessarily the case...