The Importance of Being Earnest act 1 (1895). The same lines appear, as a dialogue between Lord Illingworth and Mrs. Allonby, in A Woman of No Importance, act 2 (1893).
BookCaps, Johann Wolfgang von Goethe (2012). “Faust in Plain and Simple English: First Part of the Tragedy: (A Modern Translation and the Original Version): BookCaps Study Guide”, p.177, BookCaps Study Guides
Douglas William Jerrold, Blanchard Jerrold (1859). “Specimens of Douglas Jerrold's wit: together with selections, chiefly from his contributions to journals, intended to illustrate his opinions”, p.103