Known sourcecanonical
"How fading are the joys we dote upon! Like apparitions seen and gone. But those which soonest take their flight Are the most exquisite and strong,-- Like angels' visits, short and bright; Mortality 's too weak to bear them long."
John Norris / The Parting.
The Parting.
Bartlett's Familiar Quotations, 9th ed. (Little, Brown, 1905), public domain