Can anyone explain what a "fugue" is, in simple words?
After listening several times to Little Fugue in G minor by J. S. Bach, it seems that same "subject" is playing from start after an interval of time with a different instrument. But after listening to Toccata and Fugue in D minor, I am a bit confused and I believe fugue is not as simple as I thought.
So can anyone please explain fugue and explain its presence in these two contexts?
(Note that Bach's "Toccata and Fugue" is two separate sections; if you're looking for fugal writing in the toccata portion, you'll have some trouble!)
Fugue is a type of polyphonic contrapuntal writing (the noun is "counterpoint," and "polyphonic" means "many voices"). "Counterpoint" basically just means the relationship among written notes; it stems from the Latin punctum contra punctum, or "note against note." (The connection is more obvious in the German Kontrapunkt.)
Fugues begin with an exposition where the subject (and possibly countersubject) are introduced in each voice. Once all voices have entered with the subject, the fugue enters into one or more episodes where they develop thematic material, move through extra keys, and so on.
Types of development include elongating the (counter)subject, shortening it, flipping it upside down, playing it backwards, using only a section of it, playing it in multiple voices at the same time (but slightly staggered), some combination of all of these, etc.
There's a famous statement that "fugue is not a form, it's a process." This is because the possibilities are really limitless in terms of keys visited, types of development employed, etc. Fugues can be remarkably different, which is why it can be so difficult to explain a fugue in one sentence.
Dom's answer here is really terrific and should definitely be consulted.
And, if you're interested, check out what I think is the single most impressive example of fugal writing of all time.
Lastly, two tongue-in-cheek references:
Let me try.
The point of a fugue is to gradually explore the hidden contrpauntal potentialities of a short, distinctive melody called "subject" in an artistically compelling way. So, there are two layers of fugue-writing:
In other words: to succesfully walk your theme through a set of contrapuntal intricacies is not the end but the means; the point is to employ (a considered selection of) the contrapuntal devices to convey a specific artistic idea. The potentialities to be discovered in the subject are not merely of technical, but of artistic nature.
Also, often the composer focuses just on a single aspect of the subject's potentialities. For example, the point of the Fugue no. 1 of the Well Tempered Clavier is clearly to explore the (surprisingly many) possible different harmonizations of the subject - but not as an exercise in combinatorics, but artistically: the point is to use these different harmonizations of the subject as building blocks of a musically coherent whole in which each has its own structural function - and nothing else is allowed to distract from this goal.
The point of the E flat minor fugue, on the other hand, is purely contrapuntal: it is written in strict stillo antico and attempts to employ the widest array of contrapuntal devices such as inversion, augmentation, stretti of various sorts etc. - but all that in such a way as to achieve a seamless and "matter of course" musical texture without the least semblance of forcedness. It almost seems that the point is something like hide-and-seek: the composer does not attempt to expose the subject at each of its statements, but to hide it in the seamless texture in as many disguises as possible. Can you spot all the instances?
And so on: each successful fugue is original and unique, because the heart of the fugue as an art is the exploration of the uniqueness of a musical theme.
