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What’s the Difference Between 4/4 and C?

Music which has four beats per bar is sometimes given a 4/4 time signature, and sometimes a “C”. Is there any difference between these two different symbols? Why do they both exist?

In practice, 4/4 and C are exactly the same. We use both symbols simply because “C” is a hanger-on from centuries past!

The sign that can be used instead of the usual 4/4 time signature looks like a capital C.

common time

A lot of people think that it really is a C, and that it stands for “common time”, but that’s not really very accurate.

In the 13-17th centuries, people considered music in triple time (that is, with three beats in the bar), to be “perfect”, (something to do with the Holy Trinity – the number three has religious connections!) Perfection was represented by a complete circle, so music in triple time had a full circle as the “time signature” (the correct term for these signs is actually “mensuration sign”).

In contrast, music with 2 or 4 beats in the bar was considered “imperfect”, and was represented by a semi-circle – which happens to also look a lot like a C!

There were four basic time signatures. “Perfectum” means there were three main beats in the bar, and “Imperfectum” means two. When the beat is subdivided into three, it was called “prolatio maior” (shown by a dot), and if it is subdivided into two, it is “prolatio minor”. Here are the four old time signatures, with their modern equivalents:

mensural notation

Here’s what the C time signature used to look like in a manuscript (notice that barlines didn’t exist yet!)

facsimile mensural notation

Over time music evolved, and “C” was considered to represent four beats in the bar, rather than two. Mensural rhythms got so complicated that almost nobody could understand them, and the modern “fraction-style” time signatures were invented. But “C” was a convenient and quick symbol, and continued to be used widely.

We still use another one of the old “mensuration signs” today – the C with a vertical line through it.

cut common time

The semicircle showed that the time was “imperfect”, and the vertical line made it “tempus imperfectum diminutum – to be played twice as fast as normal imperfect time. All four of the old time signatures could have a line through them for the same effect.

Today we use the symbol to mean the same as 2/2. We call this time signature “alla breve”, because when it was first used, the main beat was a breve (double whole note). Today, of course, the main beat of 2/2 is the minim (half note) – this is because all the note lengths we use today used to be played more quickly hundreds of years ago. (“Breve” is related to the word “brief”, and used to be one of the fastest notes available to composers!) This symbol is also known as “cut common time”.