“Semel insanivimus omnes” is not from Horace but from Mantuanus, an Italian. In a work entitled “De honesto amore” is this line,
Id commune malum, semel insanivimus omnes.
Dryden in ‘Absalom and Achitophel’ has these lines,
David for him his tuneful harp had strung
And heaven had wanted one immortal song.
Pope in his Epistle to Arbuthnot has
Friend of my life which did not you prolong
The world had wanted many an idle song.
Tickell's lines