Robert P. Langlands

Author's comments: There is as yet no text with the title Functoriality and Reciprocity. Begun as preparations for a lecture, the text appearing here was, and remains, a first attempt to come to terms with the two topics of the title, an attempt that is perhaps doomed by its nature and by my years to remain provisional.

Author's comments: This paper was prepared for a meeting in Bialowieza that I was unable at the last minute to attend. It has appeared in the proceedings of that conference, Twenty years of Bialowieza: A mathematical anthology. The paper was intended as a beginning.

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Auhor's comments: Although I have the feeling of having left unfinished almost every mathematical project undertaken, the study of endoscopy and the stabilized trace formula was, in this respect, one of the most unsatisfactory of all. It went on for a very long time without reaching any very cogent conclusions. This now seems with hindsight to have been inevitable. The efforts of a number of excellent mathematicians make it clear that the problems to be solved, many of which remain outstanding, were much more difficult than I appreciated.

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