All evening long you have been singing various parts of chant. I don’t understand how it is that chant people just start singing on any note. There’s no piano, no pitchpipe, no keyboard or recording. You just start singing and then the music comes out. How do you do that? Is it perfect pitch? How do you know where to begin?
This is the sort of question only a trained musician would ask. For anyone else, the question probably doesn’t make any sense. I mean, if you are going to sing “Happy Birthday” you just start singing, right? Well, the trained musician is puzzled at how you can pick up a piece of music and just start singing it without knowing what note to start on.
The answer speaks to the remarkable flexibility of chant notation. It actually doesn’t matter where you start. All that matters is that you keep the relationship between the notes correct. There are only two possible ways that one note can be related to another note: whole step or half step. All music consists of combinations of those two things. The starting place doesn’t matter at all so long as you preserve those relationships.
This is not obvious at all from the way we conceive of music today: this is a C, this is a B, this is an Eb and so on. This is not the case with chant. It can start on a pitch that is best for the human voice. To sing a chant you only need to start singing.
As with many aspects of chant, the truth is much simpler than the perception. This is why sometimes people with no training in modern music make better chanters than people with years of training. Without training, you have nothing to unlearn, which is a huge advantage.