That part of a work of one author found in another is not of itself piracy, or sufficient to support an action; a man may adopt part of the work of another; he may so make use of another’s labors for the promotion of science and the benefit of the public. – Lord Ellenborough, quoted in Bouvier’s Law Dictionary by John Bouvier, 8th

An anthology of quotations is a museum of utterances. – Gary Saul Morson, The Words of Others: From Quotations to Culture, 2011

It’s a strange world of language in which skating on thin ice can get you into hot water. – Franklin P. Jones

In these circumstances I think we must take the bull by the horns… and, making due allowances, quote whenever we feel that the allusion is interesting or helpful or amusing. – Clifton Fadiman, c.1955