Analysis of A Bird Song.

It's a year almost that I have not seen her:
Oh, last summer green things were greener,
Brambles fewer, the blue sky bluer.

It's surely summer, for there's a swallow:
Come one swallow, his mate will follow,
The bird race quicken and wheel and thicken.

Oh happy swallow whose mate will follow
O'er height, o'er hollow! I'd be a swallow,
To build this weather one nest together.