It is fitting that Professor Dirk Jan Struik be greeted with this melange of mathematical, scientific, historical, sociological and political essays. The authors are also appropriately varied: different countries, outlooks, religions, generations, and we suppose - of course we did not as- different politics too. Many more would have joined us, we know, but the good friends in this book make a fine and representative assembly of the intersection of two (mathematical!) classes: affectionately respect­ ful admirers of Dirk Struik, and the best thinkers of this troubled century. Struik has been among the most steadfast supporters of the Boston Colloquium for the Philosophy of Science, that