Steven Johnson posts an interesting remembrance of Jacques Derrida, which includes this gem of an observation:
[Derrida] once showed up as a surprise guest at a graduate seminar Spivak was teaching on his work — he arrived before Spivack did, and so there was a hilarious period for about ten minutes where all these over-caffeinated grad students had to resist the urge to ask the quiet, white-haired man in the corner if he was, in fact, Derrida. In a way, his appearance was a strange corrective to the general thrust of his theories. You spend six years cementing the idea that the Author is irrelevant, and that you’re free to erect new interpretations without his permission. It’s all fun and games, until one day you start riffing around the seminar table and you realize that the Author is sitting right next to you, taking notes.