Audio: canon (0:12)

Figure: canon
Octave below134dn5up6
Octave above134up5dn6
Fourth below23up4dn5up6dn7
Fourth above23dn4up5dn6up7
Table: canon

canon plays a canon on an atmosphere synth. The canon figure shows the score and the table lists the leader motion which will result in a consonant interval (1 = unison, 2 = second, 3 = third and so on):

  • The upper part is the leader melody.
  • The lower part is the follower melody at a fourth below.
  • Bars 1-12 show the draft canon in first species counterpoint.
  • Bars 13-24 show the draft canon expanded to fifth species counterpoint.

A canon is a self harmonising melody written in counterpoint.

A canon with two parts is called a canon in two. The first and second parts are respectively called the leader and follower, or dux and comes, if you prefer Latin. A canon in two at unison is a two part canon in which the follower is a replica of the leader. A canon in two at the fourth below is a two part canon in which the follower is transposed by an interval of a fourth below the leader.

Canon, like round, contains only one melody. The leader melody is exactly the same as the follower melody. The only difference is that the follower is offset in time. In canon the follower is offset by one bar.

A canon can be written using the sectional approach shown in writing a round. This a perfectly viable approach and many canons appear to be written this way.

canon is written in two stages using a technique that is not sectional.

The first stage is to write a draft in first species counterpoint, as shown in bars 1-12 of the score. However, the motion of the melody is not ordered, as it would be in traditional first species. Instead of moving by step, the melody moves by consonance. Consonant motion in the leader melody guarantees that the harmony will also consist of consonant intervals. The reason is that the intervals formed between the notes of the leader melody are exactly the same intervals that will appear later in the harmony between the leader and follower. This insight enables a melody to be written in such a way that the motion of the notes only produces consonant intervals. The only constraint is that of contrapuntal motion, avoiding direct motion to a perfect consonance.

Take the example of canon at a fourth below. The canon table shows that the melody can move by step up or down and this will result in consonant intervals of a fifth or third. The melody can also move by a third up as this will result in a consonant sixth. It cannot move by a third down because this will result in a dissonant second. As long as the melody moves according to the intervals in the table the result will be consonant intervals in the melody and in the harmony.

The second stage is to expand the draft to fifth species counterpoint using all the tricks of trade and being as florid as you wish, as shown in bars 13-24 of the score.

Writing a canon is similar to solving a crossword puzzle. You might like to follow in the footsteps of other composers and write what is called a puzzle canon for personal amusement and the delight and edification of others.