Young Love III - "But, Song, arise thee on a greater wing,"

But, Song, arise thee on a greater wing,     Nor twitter robin-like of love, nor sing     A pretty dalliance with grief - but try     Some metre like a sky,     Wherein to set     Stars that may linger yet     When I, thy master, shall have come to die.             Twitter and tweet                 Thy carollings                 Of little things,             Of fair and sweet;             For it is meet,                 O robin red!             That little theme                 Hath little song,                 That little head             Hath little dream,                 And long.     But we have starry business, such a grief     As Autumn's, dead by some forgotten sheaf,     While all the distance echoes of the wain;     Grief as an ocean's for some sudden isle     Of living green that stayed with it a while,     Then to oblivious deluge plunged again!     Grief as of Alps that yearn but never reach,     Grief as of Death for Life, of Night for Day:     Such grief, O Song, how hast thou strength to teach,     How hope to make assay?