What is the meaning of Frost's Fragmentary Blue?

I came across this poem and was wondering what it means.



Here's the poem:

Why make so much of fragmentary blue

In here and there a bird, or butterfly,

Or flower, or wearing-stone, or open eye,

When heaven presents in sheets the solid hue?

Since earth is earth, perhaps, not heaven (as yet)--

Though some savants make earth include the sky;

And blue so far above us comes so high,

It only gives our wish for blue a whet.