I've recently begun on trying to compose a Cantus Firmus (it's an assignment given to me by my teacher). I know some of the rules but there are some parts I guess I don't understand: Could it be in any key signature? What about clefs? I've searched online but I've mostly seen the style written in Alto clef. ![enter image description here

this is what I've done so far for the Alto version. After the climax is went down a 4ths instead of going down in step wise motion. As for the treble clef version, I've done the same as well after the climax. Are there any rules I would be breaking? enter image description here

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    A cantus firmus is, at root, just a melody, so clef is according to who should sing that part, and key signature is up to you -- unless your teacher specified otherwise in the assignment. – Aaron Nov 16 '20 at 0:29
  • @Aaron is the way I noted this correct in a sense? Now that I understand that there is no limit in terms of clefs and key signatures. – Leffles Nov 16 '20 at 0:51
  • They seem okay to me, but this is not my expertise. – Aaron Nov 16 '20 at 0:57
  • Looks like you replaced the wrong c.f. There are two treble clefs (both without the q=150) but no alto. – Aaron Nov 17 '20 at 16:17

It's hard to believe you would be given an assignment to write a cantus firmus but not have a text book or syllabus for procedures. The whole point of species counterpoint is to learn about rigorous compositional procedures. How can you do that without the procedures? If you did get that, ask for it.

Here is an example syllabus for a counterpoint class and it gives a list of rules for the cantus firmus.

You can also get similar stuff from other counterpoint books. Look for Fux's Gradus that's the classic text. Goetschius' Applied Counterpoint has a detailed intro for melody rules, although it isn't specifically labeled cantus firmus.

Some of the rules I've seen in various sources:

  • start and end on the tonic
  • use a modest range like an octave or tenth (it should be easily singable, that's the real goal of the cantus)
  • move by step, diatonically (except the penultimate note may be a raised leading tone like C# in D dorian ... and some others like a lowered subdominant in lydian, etc.)
  • keep leaps small, generally the max is a perfect fifth (an octave is acceptable too)
  • resolve leaps by step in opposite direction
  • melodic contour-wise place the climax, highest note around middle or slightly after middle of the melody

Some avoids:

  • avoid chromatic, augmented, diminished, or tritone melodic intervals
  • avoid repeating a note too many times, max of three
  • avoid repeating figures or melodic sequence
  • avoid outlining a triad (I think I have seen this somewhere, but can't quote it)

You cantus seems fine to me, but the opening outlines a triad, and mm. 7, 8 and 9, 10 are a melodic sequence.

Clef and key don't matter.

One final point: don't get too hung up on the "rules." The cantus firmi that Fux presents in the Gradus include example of consecutive leaps, leaps resolve with leaps, etc. Try to stick to the rules for the sake a rigorous study, but understand they aren't inviolable.


I see a couple of mistakes here, compared to the cantus firmi taught by Fux. Is your teacher using the Fux? Observations below:

  • 2nd species counterpoint typically given the unit pulse so much counterpoint is written in cut time.
  • The range of your treble cantus firmus exceeds a perfect fifth.
  • Both of your examples have spots where there are two skips (“skip” defined as movement by a 3rd; “leaps” are for intervals a 4th or greater) in a row; double skips must immediately proceed by step in the opposite direction.

In two-part counterpoint the cantus firmus is traditionally the lower voice as its rhythm is static and therefore serves to ground the composition. In three-part counterpoint it’s traditionally a low or middle voice, more commonly a middle voice as the middle is the easiest way to ground a composition without becoming obtrusive.

Keep in mind my comments are with respect to strict 17th century technique. Counterpoint practices evolved with each century.

That said, you should pick up “gradus ad parnassum” by Fux if you’re serious at all about counterpoint.

Also, as an aside, many classical musicians would not take the 150 tempo mark seriously, as many tempo indications in the classical tradition revolve around analog metronome speeds.

  • This doesn't fully jibe with my understanding of Fux. Are they specific to the rules for the c.f.? For counterpoint voices, the rule about a skip being followed by a step in the other direction is specific to skips of a fourth or larger. Fux also makes a point of placing the c.f. both above and below the counterpoint in two-part exercises. And as I recall, counterpoint voices are not restricted to the range of a perfect fifth. – Aaron Nov 16 '20 at 12:03
  • BTW, nice to see you posting again. I joined since you last posted, and until now, I'd only encountered your entries from "long ago" in MP&T terms. Good stuff, and I look forward to reading more. – Aaron Nov 16 '20 at 12:07
  • I'll look into more of what you've just mentioned... As for the tempo of 150 I have accidentally placed that there. Forgot to mention not to pay attention to it. But I've edited it now. – Leffles Nov 16 '20 at 16:38
  • Since your first bullet point has nothing to do with Fux (the metronome having come into common use roughly 90 years after Gradus ad Parnassum was published), the answer would probably be improved if that were mentioned somewhere else. (Since that is a relatively minor point, I have upvoted.) – phoog Nov 16 '20 at 17:03
  • @phoog - valid point; was still groggy after waking up and was maybe a little salty too. Yep I’ll change it. – jjmusicnotes Nov 17 '20 at 3:21

Canto fermo is simply put, any piece of melody taken as a basis for composition. Italian for 'fixed song'.

So, any basic melody (often initially secular) usually used in ecclesiastical ways could be termed canto fermo. Also known as 'vox principalis' it formed the basis for a song. That melody line was then used to produce a 'harmony' a fourth or fifth away, in a sort of doubling effect. Maybe that's what your teacher is looking for, but basically any melody can be canto fermo.

  • "Canto fermo" is Italian for "I stop singing". "Cantus firmus" is Latin for "fixed song." Britannica has a nice definition of Cantus Firmus the includes some additional historical detail regarding the evolution from "vox principalis" to "cantus firmus". – Aaron Nov 16 '20 at 12:30
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    While this answer is correct to a certain degree (and, in general, it is a point well worth making), it ignores the fact that historical composition treatises developed rules governing cantus firmus composition. In the context of a composition class, therefore, which is the context of this question, the student will want to understand how to apply those rules. This answer isn't particularly helpful for that purpose. – phoog Nov 16 '20 at 17:02

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