This is not a normal book. It is a collection of transcripts of talks that I gave between the year 2003 and now. I gave most of these talks on the spur of the moment, without making notes ahead of time. (“Impromptu” is the usual term for that dangerous way of speaking.) One of the “talks” is not a transcript, but a set of notes for a talk I never gave. Any organization or order in the talks is purely coincidental—or (...) at least it’s not all my fault. (shrink)