From the recently published book-length interview Although Of Course You End Up Becoming Yourself:

“I’m not biochemically depressed. But I feel like I got to dip my toe in that wading pool and, um, not going back there is more important to me than anything… It’s worse than any kind of physical injury, or any kind of – it may be what in the old days was called a spiritual crisis or whatever. It’s just the feeling as though the entire, every axiom of your life turned out to be false, and there was actually nothing, and you were nothing, and it was all a delusion. And that you were better than everyone else because you saw that it was a delusion, and yet you were worse because you couldn’t function. And it was just, it was horrible. And trying to be at Harvard, and to read about “freedom of the will” with John Rawls while thinking this way was just extremely unpleasant.” (p. 67-68)