Ramsey, for Auld Lang Syne

A stroll taken around the landscape of Ramsey's Theory. One way first, "Down from infinite to finite", then, another way, "Up from disorder to order". An expose' made at the "Rencontres arithme'tique et combinatoire", Saint-Etienne, june 2006.Comment: The english version (p. 1-9) is followed by a french version (p.9-19