Related
A canon has one requirement: one melody followed faithfully all the way to the end, nothing omitted.
Imitation only needs "say one line back". A canon requires following from the moment of entry to the end.
So the relation is:
Imitation is the device; a canon is imitation taken to its limit. (See imitation.)
The simplest form and the axes of variation
The simplest canon enters at the unison — the second voice starts the same melody a bar later. That is round singing (as in "Frère Jacques"). It is also very hard to write without collisions, because the two voices are permanently one fixed step apart.
Change the "following rule" and you get different canons:
| Axis | Method | Result |
|---|---|---|
| entry spacing | a bar / two bars / half a bar | the shorter the tighter (the extreme is a stretto) |
| entry interval | unison / octave / fifth / other | fifths and fourths introduce modal colour changes |
| direction | the following voice sings the melody upside down (mirror canon) | the lines move in opposite directions yet still pair (see [[concept:contrapuntal-devices |
| time | double or halve the note values (augmentation / diminution canon) | one voice turns into "slow motion" and the texture widens at once |
| direction and time | retrograde (back to front) and similar | extreme devices, mostly for strict-writing study |
One common misunderstanding that must be cleared up
Pachelbel's Canon in D is not strictly "a canon".
It has two layers:
| Layer | Writing |
|---|---|
| bass | a two-bar ground bass (ostinato) repeating (see [[concept:pedal-point |
| three violins above | these are the canon — three voices following strictly |
In other words: the bass is not the canon; the parts above are. The whole piece is a combination of ground bass and canon. It is usually shortened to "Canon" because the upper layer is so striking that it hides the structure — but accurately, it is ground-bass variation combined with canon.
How it differs from a fugue
Both rest on imitation, but with different goals:
| Canon | Fugue | |
|---|---|---|
| Following | strict throughout (nothing omitted) | the subject enters repeatedly, linked by episodes |
| Free passages | essentially none | yes — episodes are exactly that |
| Means of development | changing the rule (interval / direction / time value) | the subject entering in different keys and combinations |
| Relation | more rigid, closer to mathematics | more flexible, admits rich harmonic change |
In one line: a canon takes the rule to its limit; a fugue takes the material to its limit.
Diagram: the canon's fixed lag
Listen: the entry interval
A canon needs two voices, and this site's components are single-voice — so interval demonstrates the interval of the canon's entry (the height at which the second voice comes in), one of its key variables. For the actual fixed-lag effect, use the instances: Bach's Goldberg Variation 12 (atepp-002452) is the shortest and clearest.
Common misconceptions
- "A canon means Pachelbel's." A canon is a way of writing; there are countless works. And in Pachelbel's
- "A canon must be identical throughout." That is only the simplest form. Mirror, retrograde, augmentation and
- "A canon is just a round." Round singing (unison canon) is the easiest kind; most canons are far more
- "Canons are easier than fugues." A canon's constraints are tighter (strict throughout), it simply has
piece only the three upper violins are the canon — the bass is a ground bass.
diminution canons are all legitimate variants.
complex.
fewer means of development. The two are difficult in different directions. :::
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Sources
- 卡农指同一旋律在不同声部按固定规则严格追随的复调写法，属对位学通则
- 变形卡农（倒影 / 逆行 / 增值 / 减值）与"不同间隔、不同音程"的进入方式为通行对位教学表述
Used for fact-checking only; all prose is original.