I always tell my students there are many 3‘s in piano playing:
For playing each note there are 3 steps-
1. preparation, 2. execution and 3. release.
When there is a repetition for a phrase, it must be 3 times-
1 is only a statement, 2 is not enough to stress the importance, so 3 is the perfect repetition.
In a sonata form (usually occurring in the first movement of a piano sonata), there are 1. exposition, 2. development, and 3. recapitulation. And in a classical piano sonata there are usually 3 movements.
In time signatures, the triple time 3/4 came first. It was once regarded as the perfect time and its representing symbol was a circle “O”, possibly referring to the trinity. Quadruple time 4/4 was the broken circle, the “C” symbol as we are familiar with. The symbol that represents duple time 2/2 is the “C” with a vertical line across it.
When we are playing a piece,
1. we should be aware of what we has just played through (the past), even we might have made mistake in the past we must forgo it; however,
2. we must realize and focus on that we are now in the process of playing (the present), and
3. we must look and go forward (the future).
Just as we are playing a piece, we ourselves are in the situation of a trinity, that:
1. We are fully aware of what we have been through in the past, about all the good and bad experiences in piano learning, exams and performances; yet
2. we should not stop at the past, rather we focus on what we have now, that we are grateful of how far we have come and improved and what we can do better with our playing and learning, so that;
3. we know and are confident that we can progress further in the future, near or far.
Note: I am not a religious person.