 During the 1940s it occurred to several people (chiefly Anatolii Mal’tsev in Russia, Alfred Tarski in the USA and Abraham Robinson in Britain) that the metatheorems of classical logic could be used to prove mathematical theorems about classes defined in the two ways we have just described. In 1950 both Robinson and Tarski were invited to address the International Congress of Mathematicians at Cambridge Mass. on this new discipline (which as yet had no name – Tarski proposed the name ‘theory of models’ in 1954). The conclusion of Robinson’s address to that Congress is worth quoting: