http://ift.tt/2dSnNzV The Bourbaki wedding invitation is probably the most effective branding- and marketing-campaign in the history of mathematics. It contains this, seemingly opaque, paragraph: The trivial isomorphism will be given to them by P. Adic, of the Diophantine Order, at the Principal Cohomology of the Universal Variety, the 3 Cartember, year VI, at the usual hour. Bourbaki wedding card It was pretty easy to decode the date of the wedding “3 Cartember, year VI” to be June 3rd, 1939, and (a bit more difficult) the wedding place “the Principal Cohomology of the Universal Variety” as the l’église royale Notre-Dame du Val-de-Grâce in Paris. The identity of the celebrating priest “P. Adic, of the Diophantine Order” remained unclear. The most likely suspect was Helmut Hasse , but I couldn’t place him in Paris on June 3rd, 1939. Hasse is the central figure in the title picture, taken in Oberwolfach in 1952, before one of his cars. Here’s another picture of car-freak Ha...