Content but Empty of Content

Zero is not a number,
Is the absence of number.
Absence must be everywhere,

Since math won’t work without it,
And yet, absence seems nowhere
When you search for it. Almost,

Here and there, past atmospheres,
Past stellar winds, almost there,
But no perfect absence there.

If you need it and use it,
Juggle telescopes with it,
Balance infinity’s books

And your own accounts with it
That by definition can’t
Itself be in existence,

What is it, zero? Is it
What isn’t? Then why need it
To keep what is, this content?