William Cowper (1849). “The Complete Poetical Works of William Cowper, Esq., Including the Copyright Poems, with a Life of the Author, from the Edition of Robert Southey”, p.222
Edgar Degas' remark in a conversation with the writer Moore (circa 1875), as quoted in Sue Roe "The Private Lives of the Impressionists" (p. 117), 2006.