Everything seems fine until you're about 40. Then something is definitely beginning to go wrong. And you look in the mirror with your old habit of thinking, 'While I accept that everyone grows old and dies, it's a funny thing, but I'm an exception to that rule.'
You take your life in your own hands, and what happens? A terrible thing: no one to blame.
A complacent satisfaction with present knowledge is the chief bar to the pursuit of knowledge.