Known sourcecanonical
"Take, O boatman, thrice thy fee,-- Take, I give it willingly; For, invisible to thee, Spirits twain have crossed with me."
Johann L. Uhland / The Passage. Edinburgh Review, October, 1832.
The Passage. Edinburgh Review, October, 1832.
Bartlett's Familiar Quotations, 9th ed. (Little, Brown, 1905), public domain