… is from page 251 of the 1992 collection of some of William Graham Sumner’s best essays, On Liberty, Society, and Politics (Roger C. Bannister, ed.); specifically, this quotation is from Sumner’s 1894 essay “The Absurd Effort to Make the World Over”:
Writers very often assert that something never existed before because they do not know that it ever existed before, or that something is worse than ever before because they are not possessed of detailed information about what has existed before.
