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 ā3 Cartember, year VIā to be June 3rd, 1939, and (a bit more difficult) the wedding place āthe Principal Cohomology of the Universal Varietyā as the lāĆ©glise royale Notre-Dame du Val-de-GrĆ¢ce in Paris. The identity of the celebrating priest āP. Adic, of the Diophantine Orderā remained unclear. The most likely suspect was Helmut Hasse , but I couldnāt 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. Hereās another picture of car-freak Ha...