What does this word mean?
It turns out that it has two very different meanings because composers gradually began to use the word very differently starting in the Romantic period. In the time of Bach, a prelude was an introduction. It was most often the first piece in a set. Later it often just became a free-form composition that could be anything in the world.
In Bach’s preludes and fugues, the prelude was the first piece in a st of two, and the fugue was the second one.
In a suite the prelude was the first piece followed by several other pieces, all with the names of dances. A prelude was also an orchestral introduction to an opera, and that meaning never went out of fashion It is still valued valid right through to the present day.
By the time of Frederic Chopin a new meaning was invented.
By the Romantic period a “prelude” was simply any piece of music in free form, and it was usually – but not always – somewhat short. However, what we mean by “short” is very relative, so by the time of Claude Debussy a short prelude for orchestra might be 15 minutes long.
A great example is Claude Debussy’s “Afternoon of a Fawn”.
Because of our modern conception of what a prelude is, by the Romantic period, which started roughly in the early 1800s and it is really still going on right now, people began assembling sets of preludes. We don’t know if Bach ever had any such thing in mind or would have approved of this idea. However, editors began assembling sets of preludes, so you will see “12 Little Preludes” by Bach and “Six Little Preludes” by Bach, as if somehow he had these pieces in mind as belonging together.
He most definitely did not.
As a result we now have collections whose individual pieces have been assembled rather arbitrarily following two very erroneous preconceptions. First of all, the attempt to put all of Bach’s compositions in chronological order did not have any kind of success until the 20th century, and even now historians are finding gross errors in the system. Second, these collections give listeners and performers a very false idea of how Bach composed and how he ordered his own music.
The attempt to put these pieces in chronological order are absolutely inaccurate in all ways. Such collections did not effectively group the selections well according to mood, tempo and their key signatures. Thus these collections are nothing more than editors half-baked attempts to group things that were never meant to be grouped in the first place.
As a result we have a gigantic mess. What in heaven’s name is a short prelude? What is a long prelude? What is an easy prelude or a hard prelude? How do any of these compositions get labeled? The answer, once again, is that these collections came about through totally arbitrary choices and are utterly useless for teaching and for performance choices.
BWV, the meaning…
One more thing: “BWV Bach numbers” are an attempt to order his music chronologically. We already know these numbers are often incredibly wrong, so any attempt to group preludes in the time of Bach according to when they were written is going to fail totally.
For this reason, when I play the music of Bach I simply pick the preludes that I like and record them with no plan in mind whatsoever other than to entertain myself and those who are listening as I present the music. However, if I were performing in public I would do exactly the same thing that Romantic composers did. I would pick a few, probably three, then perform them as a set. I would consider the keys, moods, and tempos to make a performance as attractive and stimulating as possible.
For all these reasons I totally reject what has been done in the past and frankly believe that Bach would prefer my idea to the horrendous collections from the Romantic period. That was a bad idea from the very start.