Now that's what I call green (sorry for the turquoise remark before).
These are beautiful.
The whole poem is 72 lines long. Your quote comes after line 48. It continues as follows:
Here at the fountain's sliding foot,
Or at some fruit tree's mossy root,
Casting the body's vest aside,
My soul into the boughs does glide;
There like a bird it sits and sings,
Then whets, and combs its silver wings;
And, till prepar'd for longer flight,
Waves in its plumes the various light.