W (who has been fidgeting with the poker) asks for an example of a moral rule. P replies 'Not to threaten visiting lecturers with pokers', at which W storms out. In Wittgenstein's Poker
Edmonds and Eidinow explain that it probably didn't happen quite that way. But this book is far more than just a discussion of a 10 minute incident involving Karl Popper and Ludwig Wittgenstein in Cambridge in 1946. Rather it gives a critical look at the lives of the two philosophers, including their upbringings (both came from Jewish families in Vienna, and so both were faced with the problems of the rise of Hitler), their points of view, and how they interacted with those around them.
Sometimes, I have to say, I wondered what the point of this book was. It isn't really a 'learn philosophy via biography' sort of a book. And if the question is whether individual incidents such as this particularly matter in the development of philosophy, well the impression I got was that no, they don't, in which case the authors seem to be sawing off the branch on which they are sitting. But it was a thought provoking book. For example, why does someone become a professional philosopher, rather than a cabinet maker (which Popper was for a while) who just likes to think about things. If such questions interest you then you should have a look at this book.