Grocott & Ward, comps. Grocott’s Familiar Quotations, 6th ed. 189-?.
Oil
Whence is thy learning? hath thy toil
O’er books consum’d the midnight oil?
Gay.—Shepherd and Philosopher, Line 15; Gay’s Trivia, Book II. Line 558; Shenstone, Elegy XI. Verse 7; Cowper, Retirement; Lloyd, On Rhyme, and Author and Friend.