Why study Wittgenstein's diagrams?

This was the title of a seminar that I gave at the Wittgenstein Archives at the University of Bergen in November 1992. The present conference, at which we are undertaking a review of Wittgenstein's works 50 years after his death, would seem to present an opportunity to revisit this title and consider how one might respond in 2001. In 1992 I felt that I did not have a strong argument on which to base my case for a defence of such a study. However, the lack of previous studies seemed surprising.....