Note 17 — 440.
Reading edition
The poem to which Gibbon alludes is the Essay on Epic Poetry in five Epistles to the Rev. Mr. Mason (London, 1782). Hayley's mother was Mary Yates (1718-1775), who married Thomas Hayley in 1740, and died in 1775. The lines to which Gibbon alludes occur in the fourth epistle (ll. 439 to end).
"Nature, who deck'd thy form with Beauty's flowers, Exhausted on thy soul her finer powers; Taught it with all her energy to feel Love's melting softness, Friendship's fervid zeal, The generous purpose, and the active thought, With Charity's diffusive spirit fraught; There all the best of mental gifts she plac'd, Vigor of judgment, purity of Taste, Superior parts, without their spleenful leaven, Kindness to Earth, and confidence in Heaven."