You beat your pate, and fancy wit will come;
Knock as you please, there's nobody at home.

On a Dull Writer, reported in John Hawkesworth, The Works of Jonathan Swift, D.D., Dean of St. Patrick's, Dublin (1754), p. 265. Alternately attributed to Alexander Pope by Bartlett's Quotations, 10th Edition (1919). Compare: "His wit invites you by his looks to come, But when you knock, it never is at home", William Cowper, Conversation, line 303