It's called "Advice to a Beginning Graduate Student":
While the whole thing is quite wonderful, the piece that has been wreaking all sorts of havoc in my head this week is the idea that writing makes us smarter.
You know what FINITE AUTOMATA can do.
You know what TURING MACHINES can do.
For example, Finite Automata can add but not multiply.
Turing Machines can compute any computable function.
Turing machines are incredibly more powerful than Finite Automata.
Yet the only difference between a FA and a TM is that
the TM, unlike the FA, has paper and pencil.
Think about it.
It tells you something about the power of writing.
Without writing, you are reduced to a finite automaton.
With writing you have the extraordinary power of a Turing machine.
And you start thinking about that, maybe with your pop psychology hat on for a minute, and realize that being in a certain "state of mind" is just a badly-made FA, where you loop and loop through the same state, never really breaking out of it. And if maybe you're depressed, you do some cognitive-behavioral therapy and fix it by converting that state of mind to something explicit, almost a program that is external to that state entirely.
Maybe back to getting things done in the real world, you think why there are limits to what you can talk about or how much you can get done in a verbal meeting, because your short-term memory is more equivalent to a FA than to a Turing Machine, with its rather large amount of tape. So to really make complicated things or organize complicated tasks, you again have to write them down.
And then again, you think of the successful user experiences, and how amazingly the Facebook news feed is almost literally a tape that a Turing Machine would use, a sort of written record that can be read and written...all of life but in a very linear fashion.
There are dozens more, but it makes it very easy to say that our written language is the most important invention, ever.