Buster Keaton is essentially the comedian of order, of logic; aloof, deadpan, isolated in his contests with the implacable machine &ndash: a runaway train, in this instance &ndash: he operates with a calm assurance that his inadequate resources will eventually tame the monster.

It is his conflicts with and relationships to' various machines &ndash: the train in "The General", the enormous coffee &ndash: pot in "The Navigator" and more recently the piano in "Limelight" that lie at the centre of Keaton's work. He is not, so it seems, concerned at all with his audience as are so many of the other great comics. He is the most detached of actors, in appearance quite extraordinary: his head is quite rigid and looks as though it has been carved out of a chestnut; his eyes are large and staring and his face is immobile.

The entire head seems to be an inarticulate organ, expressionless and calm as a foot, and it seems to have been stuck or grated on to his lively and elastic body like some addition made of stucco or papier mache. The body is never still, but skips and jumps about with enchanting suppleness. The head that follows it, without really understanding the adventures it participates in.

In the essential detachment of his work other players, as well as the audience, are ignored and reduced to the status of so many more inanimate objects; speech, implying (or risking) communication, would destroy his isolation, and with it the development of a sustained comedy line based almost on anonymity.

In more ways than one, then, he is a “silent” comedian; and with this “silence” goes inscrutability' for all their hilarity. Keaton's films give the impression that behind the locked, melancholy face there is the mind of a mathematician for whom a succession of gags has the inevitability of an equation &ndash: to which, perhaps, only Keaton, the least imitated, the most solitary of the great comedians, knows the answer.