(con't from Part XXXVI)
"Start by doing what's necessary; then do what's possible; and suddenly you are doing the impossible."
-- Saint Francis of Assisi
The note upon which the 1st voice of an organ fugue starts is subject (no pun intended) to certain general principles with which the would-be fugue writer needs to be thoroughly familiar.
It's unrealistic to expect any online crash course in fugue writing to turn us into a fugue writer overnight, but there is much, very much, preliminary learning about it that can take place online provided we're receiving full and correct information and we're persistent in our search.
The following will illustrate this:
The 2nd voice to enter typically repeats the 1st voice, or subject, transposed up a 5th or down a 4th in the dominant tonality; this is called the answer.
The dominant key is typically chosen for the answer because scale degree 5 is the 3rd harmonic (2nd overtone) of the natural harmonic series and, save for the tonic and its octave, is the next most important note of the scale; when the answer begins in the dominant tonality it sets up a tension with the subject which has just entered in the tonic; this tonic-dominant tension is what drives all tonal music in the Western world.
The 1st note of the answer, however, and sometimes a few others as well, is sometimes transposed a 4th higher; the reason for this discrepancy has to do with harmony.
If the answer is to enter as the subject finishes, as it usually does, it generally needs to begin on a note that's consonant with tonic harmony or it will enter jarringly on an unprepared dissonance (although these days, dissonance is the norm).
For a subject that begins on scale degree 1, the answer can begin a 5th higher, on 5, which is consonant with the tonic harmony implied when the answer begins at the end of the subject, but if the subject begins on 5, the answer cannot start a 5th higher, on 2, because 2 is dissonant with tonic harmony.
Consequently, the answer is adjusted to begin on 1, a 4th higher, in order to begin on a consonance; this type of adjustment is called a tonal answer because it has been modified from its usual strict 5th transposition, this in order to confirm the tonality (tonic) by entering on a consonance, rather than conflict with it by entering on a dissonance.
After this adjustment the remaining notes in the answer are all 5th transpositions of the subject.
We read in various sources that the appearance of scale degree 5 at or near the beginning of the subject is the signal that that answer MUST be tonally adjusted, whereas if 5 does not appear at or near the beginning of the subject, no adjustment is necessary, and we speak of a real answer (a literal transposition of the subject, note for note).
The fact is, it's entirely possible for the answer to appear in the subdominant, a 4th higher than the subject rather than a 5th, with the result that no tonal adjustment in the answer is needed and a real answer will be supplied.
In this case the subject starting on the 5th scale degree is sufficient to set up a tonic-dominant tension; in such a situation, after the bridge passage following the answer brings about a return to the tonic key for the 3rd entry, the 4th entry will also be in the subdominant tonality, i.e., a 4th higher.
Due to this alternative, those who teach and maintain that all fugues which begin on scale degree 5 MUST have a tonal answer are either laboring under a serious misconception or simply not providing complete information perhaps to steer the novice away from what they consider to be any serious entanglements in their first attempts at fugue writing.
One might only examine the expositions in Bach's great d minor Toccata & Fugue for organ BWV 565 or this author's b minor Prelude & Fugue for organ Op. 26 for proof however that it can be done, and there are innumerable other examples.
Students not fully informed by this could begin to surmise, using the same reasoning, that fugue subjects DO NOT start on scale degree 3; they can presume that the answer, in this case, would have to begin on 7 (leading tone), a 5th higher than 3, and that would be impossible because tonic harmony prevails as the answer begins, dovetailed as it is with the end of the subject.
The inference here would be that it isn't possible to write a correct fugue which starts on the 3rd scale degree; when the interested student is directed to "the 48" and asked to find a single fugue there which starts on scale degree 3 and they cannot, they're tempted to accept this as proof that it isn't feasible.
There's a problem with this whole idea: while the premise may be good, we know from a reliable source (Kirnberger) that the same Bach who wrote "the 48" would never hear of it being not feasible.
It fails to take into consideration a subject which has a tail which points strongly to the dominant key; in such a case, it's not only entirely possible for the subject to start boldly on 3, but a real answer can be supplied; this too, can and has been proven, multiple times, in this author's Op. 19, 27, 29, and 30 Fugues for Organ, all of which are correctly written.
From this we may draw a corollary: any fugue subject starting on scale degree 3 MUST have a tail which points strongly to the dominant key.
If often happens in education that those individuals upon whom we habitually rely for trustworthy information can give us all the basics about it that we can stand; the trouble is, most of us students who want to really penetrate a study need more than the basics, and we need it all the time.
J.S. Bach was the greatest fugue writer in history, and he had no university education; as a fugue writer he was coached at an early age by his older brother, but he was mostly self-taught and penetrated to the core of this art through sheer hard work, an obsession to excel to the best of his ability, a dogged determination never to give up, and by doing what was necessary to his work-a-day existence, working the possibilities, and making his own discoveries; the trail he took as an emerging composer led him down every blind alley as his mastery developed.
This can be an arduous path full of cruel uncertainties; it is also the path that allowed him to put music on a plateau that no one else has ever reached, the same path that makes a really good teacher, which is why every serious organist and composer who comes after him has to be his disciple.
Likewise, when we learn our own fugue writing, it always helps to start, as Bach did, by doing what's necessary, and then do what's possible.
And suddenly, as Saint Francis observed, we find ourselves doing the impossible.