IN WHICH reference book is "fire-fighting" listed next to "funeral", and you can, with a flick, get from "monotony" to "orgy"? It is, of course, the compendious Motion Picture Moods for Pianists and Organists, an anthology of music compiled for cinema organists who were looking for material to accompany silent films.

We were treated to examples of these and many other musical moods, courtesy of Mark Kermode and his guest, the musician Neil Brand, on Silent Film (Rado 2, Tuesday). Repeated from February, this fascinating documentary comes as part of a season of programmes, The Sound of Cinema, which is being aired across the BBC.

Kermode has a soft spot for silent cinema - one that the public also developed when recently the film The Artist swept the Oscars. In that film, the importance of music in projecting emotional and dramatic information is obvious. But when the responsibility for this falls on the shoulders of live musicians, the theatrical nature of early cinema also becomes clearer.

Like the music, which is suffused with bowdlerised Wagner and Rimsky-Korsakov, this documentary was full of entertaining titbits. I, for one, had no idea that Charlie Chaplin composed the music for many of his greatest films; or that musicians were employed on the sets of silent films to create mood music for the actors.

That all this expertise was made redundant within the space of a couple of years, when talkies arrived, reveals much about a medium in which there is no place for the out-of-date. That the old is abandoned as risible is a function of promoting the new, although the studios originally adopted sound as a means of controlling what music accompanied the films, not because they thought anybody would be interested in hearing actors speak.

How did the evolution of the Hollywood dream factory influence the way in which we think about dreams? It might have made an interesting extra episode in Lucy Powell's weekday series on Radio 4 last week, Our Dreams: Our Selves, which took on the task of narrating a history of dreams and dream psychology.

It is 100 years since Freud's The Interpretation of Dreams was published. But the investigation of dreams is an ancient pursuit which even Homer dabbled in, when he has Penelope expostulate on the difference between truthful and wayward dreams entering the consciousness through gates of horn and ivory.

For much of the time, the story is about the tussle be- tween psychological and revelatory theories: Aristotle tells us that dreams are irrational and biological; and various religious traditions insist on their function as emanations of divine truth.

Most recently, it looks as if Freud is back in the game. His notion that dreams are all about wish-fulfilment, and that the ultimate purpose of dreaming is to perpetuate sleep, is now supported by the latest neurological research. Central to this is the observation that people who do not dream suffer from a lower quality of sleep. We need our dreams - however perverse or frightening they might be.