Reptilian green the wrinkled throat,
Green as a bough of yew the beard;
He bent his head, and so I smote;
Then for a thought my vision cleared.

The head dropped clean; he rose and walked;
He fixed his fingers in the hair;
The head was unabashed and talked;
I understood what I must dare.

His flesh, cut down, arose and grew.
He bade me wait the season’s round,
And then, when he had strength anew,
To meet him on his native ground.

The year declined; and in his keep
I passed in joy a thriving yule;
And whether waking or in sleep,
I lived in riot like a fool.

He beat the woods to bring me meat.
His lady, like a forest vine,
Grew in my arms; the growth was sweet;
And yet what thoughtless force was mine!

By practice and conviction formed,
With ancient stubbornness ingrained,
Although her body clung and swarmed,
My own identity remained.

Her beauty, lithe, unholy, pure,
Took shapes that I had never known;
And had I once been insecure,
Had grafted laurel in my bone.

And then, since I had kept the trust,
Had loved the lady, yet was true,
The knight withheld his giant thrust
And let me go with what I knew.

I left the green bark and the shade,
Where growth was rapid, thick, and still;
I found a road that men had made
And rested on a drying hill.

Yvor Winters

http://www.poemhunter.com/poem/sir-gawaine-and-the-green-knight/