Stephen Johnson gets to grips with classical music's technical terms
A musical prelude is an introduction to a larger piece of music. In some instances, it can stand alone as an independent piece, but most often it is heard as a preface, which may introduce musical themes that are then developed later on in the work.
Here, surely, is a musical term that’s simple enough to define. The word ‘Prelude’ comes directly from the Latin ‘praeludere’ – ‘to play before’. And that, for several centuries, was the Prelude’s function.
It was partly practical necessity. Lutenists, wanting to test their tuning and the acoustics of the room, would improvise a little warm-up piece before getting down to business.
Fitted out with the title ‘Praeludium’ this soon became a solid part of the ritual of music making. Church organists would also improvise preludes: 1) to create a suitable devotional atmosphere before the service; and 2) to flush out any incipient technical problems.
The ‘chorale preludes’ of JS Bach and his contemporaries (preludes based on a hymn tune) were generally composed with function 1 in mind – and perhaps sometimes function 2 as well.
But the fact that – on paper at least – you could have a separate, self-sufficient piece called ‘prelude’ presaged a momentous change.
In the Baroque era, most pieces called ‘prelude’ were still designed to introduce something: an instrumental suite perhaps, or a grand contrapuntal display, as in Bach’s stupendous two-volume collection of 48 Preludes and Fugues (The Well-Tempered Clavier). ven there, though, the ‘introductory’ character of some of the preludes is questionable: doesn’t the E flat major Fugue in Book I tend to sound like a relatively lightweight coda to the magnificent ‘Prelude’ that in most performances triumphantly upstages it?
Chopin may have had similar thoughts when he created the first great set of 24 Preludes – it’s tempting to call them ‘Preludes without Fugues’. But by then the word ‘prelude’ had become general Romantic currency.
The Romantics loved incompleteness: ruins, fragments, unfinished utterances that seemed to falter on the edge of the inexpressible. The notion of a ‘prelude to… what?’ fascinated them.
The score of Liszt’s symphonic poem Les préludes has a literary preface which opens with a question: ‘What else is our life but a series of preludes to that unknown Hymn, the first and solemn note of which is intoned by Death?’
And from that to Debussy’s Prélude à l’après-midi d’un faune – a work perpetually poised on the threshold of what the French call ‘le petit mort’ – may not be such a big step after all. All this from a lutenist’s warm-up . 
