On Imitation

Imitation is a musical device: it takes place when one part, called antecedent, proposes a subject, or melody (or theme); and when another part, called consequent, repeats the same melody, after some rests, and in any interval, continuing thus to the end.

In an imitation, the consequent is not always obliged to respond to the antecedent through all the extent of the subject it proposes; it may only imitate a portion, and the consequent proposing thus a new melody, becomes, in its turn, the antecedent.

Imitation may be created in various ways. It is called regular (or restricted), when response is precisely made to the nature of the intervals proposed by the antecedent; that is to say, when there is exact correspondence maintained between the tones and the semitones. In this kind of imitation, response is made to a minor second by a minor second, and to a major third by a major third, and so on.

This imitation is naturally obtained, when the consequent imitates the antecedent at the unison (or the octave). The fourth and fifth somewhat approach an exact correspondence of the intervals, but occasional accidentals are required to render it perfect; and it is almost impossible to create this identify upon the other degrees of the scale.

Imitation is called free (or irregular), when this correspondence is not maintained, and that leave is taken to respond arbitrarily to the intervals of the antecedent, according to the key in which the consequent happens to be. In this kind of imitation, response may be made to a major second by a minor second, and a minor third by a major third, etc. That is called imitation by similar movement – as the name indicates – which follows the ascending or descending motion of the antecedent; the examples above are by similar movement.

Imitation is by contrary movement, when the consequent responds by ascending motion to the descending motion of the antecedent, and vice versa. This imitation may, as well as the preceding, be regular or irregular.

Imitation by retrograde movement, is that which imitates a period or a member of a period, by taking it backwards; that is to say, the consequent begins at the last note of the period of the antecedent to be imitated, and returns to the first note.

This retrograde imitation may likewise be regular or irregular; and may equally be treated by similar movement or by contrary movement.

There are still several other sorts of imitation, of which there will be occasion to speak hereafter. At present, each of the above-mentioned kinds shall be discussed, beginning with imitation in two parts.