Page:Fugue by Ebenezer Prout.djvu/25

Chap. II.] of the implied accompanying harmony. Every musical phrase that has any meaning at all must be capable of being harmonized, probably in several different ways; and if from the first we think what harmonic progressions go best with the subject we have chosen, there will be little fear of our losing the distinct feeling of a key.

28. To illustrate our meaning we will give a few examples of simple subjects which remain in one key throughout—

If the student will examine these subjects, he will see that in both of them there can be no possible doubt about the key. Both begin with the notes of the tonic chord (the semiquaver C in (b) is only an ornamentation of the D); and both end with the descent from supertonic to tonic. The following example

is somewhat different. Here the progression is by step from tonic to dominant, and if we look at the first bar alone, the tonality is a little less decided than in the examples from Handel. But the prominence given to the dominant in the second bar fixes the key clearly, and the impression is strengthened by the subject ending on the mediant (E).

29. Our next example

is perfectly clear. The key is fixed at once by the leap from tonic to dominant at the commencement; for although the first note, E, might be the dominant of A flat, it would be most unlikely to leap to the supertonic of that key; and if it were the subdominant in the key of B flat, it would be quite unprecedented for it to leap to the tonic. Besides this, we must always mentally supply the most natural harmonies to a subject. In this case, the first chord must of course be E flat; the second will be either another position of E flat, or the chord of B flat—in either case strongly suggesting the key of E flat; and the suggestion is changed into a certainty by the A flat immediately following. In general, if a fugue subject begins with an upward leap of a perfect fifth, or a downward one of a perfect fourth, the first note will be the tonic of the key, and the second the dominant; if, on the