What gentle ghost, besprent with April dew,
Hails me so solemnly to yonder yew?
Source, in full
Elegy on the Lady Jane Pawlet, reported in Bartlett's Familiar Quotations, 10th ed. (1919); comparable to "What beckoning ghost along the moonlight shade / Invites my steps, and points to yonder glade?", Alexander Pope, in To the Memory of an Unfortunate Lady.