In T.S. Eliot's The Waste Land, he cites quite a few pieces by other poets. In this case (and the line directly preceding it) he is quoting the Prothalamion of Edmund Spenser (1552-1599), a fine poet, tho his spelling be shaky.

The poet describes a flock of nymphs (which Eliot sees depart) preparing for a wedding.

Each stanza of the poem ends with the line:

Sweete Themmes! runne softly, till I end my Song.