It's so wonderful to be kicking something around with friends who share the same interest, and I don't know how to make progress except that way. To go off in a lighthouse with nobody around would be not my idea of making progress, although surely some periods of absolute isolation are good. If you can't kick a thing around with your friends then it doesn't take shape, it doesn't gel. But that's part of it. That's forming an idea. But getting it put together in a closed form demands some sort of a deadline, a deadline of a talk, a class lecture or a paper. But I confess my principle is generally: first you say it, and then you write down what you wish you'd said.