This article is essentially a commentary on a little-known text by `Alain' (whose real name was Emile-Auguste Chartier), successively entitled Les marchands de sommeil and Vigiles de l'esprit. This piece of work, initially a prize-giving speech to students in a Parisian lycée, was rewritten by Alain many years later during the Second World War. It describes with acute intelligence and in a splendid metaphoric language the enduring and compelling proposition that the formation of critical judgement should be the ultimate purpose (...) of all teaching. (shrink)