Theodore Sturgeon Quote

It means "Ask the next question." Ask the next question, and the one that follows that, and the one that follows that. It's the symbol of everything humanity has ever created, and is the reason it has been created. This guy is sitting in a cave and he says, "Why can't man fly?" Well, that's the question. The answer may not help him, but the question now has been asked.
The next question is what? How? And so all through the ages, people have been trying to find out the answer to that question. We've found the answer, and we do fly. This is true of every accomplishment, whether it's technology or literature, poetry, political systems or anything else. That is it. Ask the next question. And the one after that.

As quoted in an interview with David Duncan (with an image of his signature).

Interview with Theodore Sturgeon