"`The smiling slopes with olive groves bedecked"

`The smiling slopes with olive groves bedecked,
Now darkly green, now, as the breeze did stir,
Spectral and white, as though the air were flecked
With elfin branches laced with gossamer;
And then so faint, the eye could scarce detect
Which the gray hillside, which the foliage fair;
Until once more it dense and sombre grew,
To shift again just as the zephyr blew.