The Written Word Keeps Asimov Immortal

Because, after he dies, everything he knows will be written down.

I'm gradually managing to cram my mind more and more full of things. I've got this beautiful mind and it's going to die, and it'll all be gone. And then I say, not in my case. Every idea I've ever had I've written down, and it's all there on paper. And I won't be gone; it'll be there.