What is the meaning of M. M. = 72 printed over a piece of music?
The M stands for "metronome," the other for the name of its inventor, Maelzl. The figures indicate the number of beats a minute and the note shows what each beat represents—in this case a quarter note. The whole annotation says that the average speed of the piece should admit of seventy-two quarter notes being played in a minute. I advise you, however, rather to consult the state of your technique and your own feeling for what is musically right in deciding upon the speed of the piece.
The Personal Element and the Metronome
In Chopin's Prelude No. 15 is the movement in C-sharp minor to be played in the same tempo as the opening movements, or much faster? How should the 6-8 and 9-8 movements of Liszt's Dance of the Gnomes be metronomized?
The C-sharp minor movement should not increase in speed, or only very little, because it rises to a considerable height dynamically, and this seems to counteract an increase of speed. As to the metronoming, I would not bother about it. The possibilities of your technique must ever regulate the speed question in a large degree. Tempo is so intimately related with touch and dynamics that it is in a large measure an individual matter. This does not mean that one may play andante where an allegro is prescribed, but that one person's allegro differs slightly from that of another person. Touch, tone, and conception influence the tempo. The metronome indications are to be accepted only with the utmost caution.
Metronome Markings May Better Be Ignored
How fast, by metronome, should the minuetto of Beethoven's Sonatina, opus 49, Number 2, be played?
If you possess an edition of Beethoven that has no metronome marks you have been singularly fortunate, and I would not for the world interfere with such rare good luck. Consult your technique, your feelings, and have confidence in your good sense.
There are Dangers in Using a Metronome
How should one use the metronome for practising? I have been warned against it, as my teacher tells me one is liable to become very stiff and mechanical by the persistent use of it.