When I started working on the history of linguistics — which had been totally forgotten; nobody knew about it — I discovered all sorts of things. One of the things I came across was Wilhelm von Humboldt’s very interesting work. One part of it that has since become famous is his statement that language “makes infinite use of finite means.” It’s often thought that we have answered that question with Turing computability and generative grammar, but we haven’t. He was talking about infinite use, not the generative capacity. Yes, we can understand the generation of the expressions that we use, but we don’t understand how we use them. Why do we decide to say this and not something else? In our normal interactions, why do we convey the inner workings of our minds to others in a particular way? Nobody understands that. So, the infinite use of language remains a mystery, as it always has. Humboldt’s aphorism is constantly quoted, but the depth of the problem it formulates is not always recognized.

The miracle that so amazed Galileo and Arnauld — and still amazes me, I can’t understand it — is how can we, with a few symbols, convey to others the inner workings of our mind? That’s something to really be surprised about, and puzzled by. And we have some grasp of it, but not a lot.

What’s my feeling of red? You can describe what the sensory organs are doing, what’s going on in the brain, but it doesn’t capture the essence of seeing something red. Will we ever capture it? Maybe not. It’s just something that’s beyond our cognitive capacities. But that shouldn’t really surprise us; we are organic creatures. It’s a possibility.

David Hume, a great philosopher, in his “History of England” — he wrote a huge history of England — there’s a chapter devoted to Isaac Newton, a full chapter. He describes Newton as, you know, the greatest mind that ever existed, and so on and so forth. He said Newton’s great achievement was to draw the veil away from some of the mysteries of nature — namely, his theory of universal gravitation and so on — but to leave other mysteries hidden in ways we will never understand. Referring to: What’s the world like? We’ll never understand it. He left that as a permanent mystery. Well, as far as we know, he was right.

Descartes, and others, when they were considering that mind is separate from body — notice that that theory fell apart because the theory of body was wrong; but the theory of mind may well have been right. But one of the things that they were concerned with was voluntary action. You decide to lift your finger. Nobody knows how that is possible; to this day we haven’t a clue. The scientists who work on voluntary motion — one of them is Emilio Bizzi, he’s one of MIT’s great scientists, one of the leading scientists who works on voluntary motion — he and his associate Robert Ajemian recently wrote a state-of-the-art article for the journal of the American Academy of Arts and Sciences in which they describe what has been discovered about voluntary motion. They say they’ll put the outcome “fancifully.” It’s as if we’re coming to understand the puppet and the strings, but we know nothing about the puppeteer. That remains as much a mystery as it has been since classical Greece. Not an inch of progress; nothing. Well, maybe that’s another permanent mystery.