Un nouveau point de repère dans la theorie des formes automorphes

Canad. Math Bulletin . 50 (2007) 243-267.

Author's comments: This paper is quite informal and I could not immediately reflect on the suggestions it contains. I am grateful to Freydoon Shahidi for suggesting that as an interim measure I write the paper for submission to the Canadian Mathematical Bulletin, where it appeared in volume 50 (2007).