Love leads me many times beneath the shade of ladies fair, whose necks are beauteous hills, and whiter far than flower of any grass; and one there cometh, clothed in robes of green, who in my heart dwells, as strength dwells in rock, and among others seems as fairest lady. and when i glance upon this gentle lady, whose brightness scatters every dusky shade, her light so smites my heart it turns to rock; i roam, as strangled, all among the hills, till i revive and am with love more green than ever yet was spring or freshest grass. this excerpt is an example of what type of poem?