Perseverance, cf. Faithfulness, Endurance, Dedication
Plato wrote the first sentence of his famous Republic nine different ways before he was satisfied. Cicero practiced speaking before friends every day for thirty years to perfect his elocution. Noah Webster labored 36 years writing his dictionary, crossing the Atlantic twice to gather material. Milton rose at 4:00 a.m. every day in order to have enough hours for his Paradise Lost. Gibbon spent 26 years on his Decline and Fall of the Roman Empire. Bryant rewrote one of his poetic masterpieces 99 times before publication, and it became a classic.