Analysis of The Snow Storm

No hawk hangs over in this air:
The urgent snow is everywhere.
The wing adroiter than a sail
Must lean away from such a gale,
Abandoning its straight intent,
Or else expose tough ligament
And tender flesh to what before
Meant dampened feathers, nothing more.
Forceless upon our backs there fall
Infrequent flakes hexagonal,
Devised in many a curious style
To charm our safety for a while,
Where close to earth like mice we go
Under the horizontal snow.