That's a very beautiful metaphor Edna, to see the emptiness of the flute as a source of creation.
Do you think the piece itself reflects this more than the name? For example using the lack of certain notes, spacings, or simply silence a source for the music?

The metaphor reminds me of Nanni Moretti beautiful film The son's room, on the emptiness which is left after a death of a person close to you.

I must say that though I am moved by the metaphor it also scares me.
If you look at the flute, as maybe Bernstein did, it works well, but what if you look at the wood from which a flute is created? To build a flute, to create, space must be made. This is a far more sinister view of the flute which can lead to murder. Space needs to be made for creation, for life, and this could be an awful excuse.

Hi George, I might not be the right person to answer your question as I don’t know the piece thoroughly since I heard it just this one time. I will just say that 2 things struck me, one being the fact that Bernstein uses, in the flute’s main theme, the dodecaphonic system of Schoenberg, a musical system and language that he considered problematic and which does not reflect Bernstein’s  usual compositional style we are  accustomed to in his more famous pieces. (One can come up with theories why, and what it represented for him, but that’s not for me.)  

As for silence, interesting that you mention it as this was the second thing that struck me, the fact that the piece ends with a long tutti section where the flute is absent until it returns right at the end and with one very long note- a most unusual ending for a big concerto piece. I am not sure though that my memory is quite precise, so I would redirect your question to the flutists.