… is from pages 428-429 of Frank Knight’s 1944 lecture “The Planful Act: The Possibilities and Limitations of Collective Rationality,” as this lecture is reprinted the 1982 Liberty Fund edition of Knight’s 1947 collection, Freedom and Reform:
Economic competition is one of the unfortunate accidents of terminology; what it means is simply the freedom of individuals to cooperate through exchange with the others who offer (or accept) the best terms.