On Fugue

The Digression, or Episode in a Fugue, is a period composed of fragments of the Subject, or of the Counter-Subjects (at the composer's own choice), with which imitations and devices are formed, and during which he may modulate, so as to introduce, in other keys, the Principal Subject, the Response, and the Counter-Subjects.

The digression may be, according to need, either short of long; and in the course of a Fugue, there should be more than one Digression, each time varying the choice of method in their treatment. When the entire composition of a fugue comes to be discussed, the places will be designated where these digressions - to which may be also given the Italian name of Andamenti - should occur; and at the same time will be shown the manner of combining them. This simple explanation of the Digression, must at present suffice.

The method that has been for some time employed for direction in the choice of modulations, consists in being regulated by the Diatonic Scale of the key in which the composition is, without modulating into chords alien to this same key. Thus, we may modulate:

• into the Dominant
• into the Sub-dominant, of which the keys are naturally major
• into the Second
• into the Mediant (or Third)
• and into the Sixth, of which the keys are naturally minor

We cannot modulate into the Seventh or leading-tone, because its fifth is not naturally perfect. That which has been here laid down, applies to the scale of the major key.

When a piece is in question, that is to be composed in a minor key, these are the methods of modulating:

• into the Sub-dominant
• into the Dominant, of which the keys are naturally minor
• into the Mediant
• and into the Sixth, of which the keys are naturally major.

We cannot modulate into the Second, because its fifth is not naturally perfect; and modulating into the Seventh should also be avoided.

Modern composers have held themselves exempt from observing, in their compositions, this simple and rational method of modulating, adopting in its stead, a much-more free, and frequently incoherent one. But if such derivations are tolerated in modern works, it is essential, and it is even expressly recommended, not to follow these erratic courses, with regard to a style of composition so severe as that of Fugue.

Thus, when a Fugue is in a Major key, the key into which we should modulate first, is that of the Dominant with its Major Third; then:

• into the Sixth, the relative minor key of the principal key
• into the major key of the Sub-dominant
• the minor key of the Second
• and to the Mediant (also minor)

And then return to the key of the Dominant, in order to proceed to the conclusion, which should be in the principal key.

It is permitted, in the course of a Fugue in a Major Key, to change the principal key into the minor; but this permutation should be employed only for a few moments, and merely to bring in a suspension on the Dominant, in order afterwards to attack the Principal Major Key.

When a Fugue is in a minor key, the first modulation is into the Mediant Major Key, which is the Relative of the Principal Key; then we modulate alternately either into the Dominant minor key, or into the Sixth Major Key, or into the Sub-dominant minor key, or into the Seventh Major Key; and lastly, by means of one of these keys, return to the principal key. That we may terminate in the like way with the Fugue in a Major Key, the minor principal key may be changed into major, under the conditions that were shown with regard to the Fugue in a Major Key.

This is what refers to the modulation of a piece. The chief difficulty in the art of modulating, is the choice of the chords in their succession, in order to go from one key into another, in a manner that shall be natural and suitable to the one into which we are passing; and so that there shall be nothing in these transitions to hurt the ear or the taste.

Experience, that practice alone can give, will smooth those difficulties to which the want of both gives rise.

Having passed in review all that relates to the elements of a fugue, there remains but to treat of its entire composition. It has been already said, that the indispensable conditions of a Fugue are:

• the Subject
• the Response
• the Counter-Subject
• and the Stretto

The Accessory (or Episodical conditions) are: the Imitations formed by Fragments of the Subject, or of the Counter-Subject, and with which are composed the different Digressions or Andamenti which should occur in the course of a Fugue. All these elements suffice for the construction of a short and ordinary Fugue. But if, in a composition of this sort, other combinations and devices be introduced, a more-extended and varied while will be the result. It is difficult to determine the number of devices that may be introduced into a Fugue; their choice and amount depend upon the nature of the Subject, of the Counter-Subject, and upon the comparatively experienced skill of the composer. There is no Fugue, which does not differ from another, either by its mode of conduct, or by its combinations; this difference and variation are the effects of fantasy, and of an imagination and invention more or less fertile; industry, the facility it gives, and the experience derived from both, by cultivating the imagination, directs a composer in the choice of ideas and of means for the judicious construction of a Fugue.

Each composer bears - so to speak - his own distinctive mark, in this respect; it is requisite, therefore, to examine and analyze many Fugues of the best masters, in order to become thoroughly versed in this style of composition.

The next section provides different examples of Fugue in two, three, and four parts. These examples, enforced by remarks, will suffice to demonstrate how the plan of a simple and ordinary Fugue should be constructed; and how that of a Fugue more extended and more complicated, by the introduction of several devices.