I am reminded of the professor who, in his declining hours, was asked by his devoted pupils for his final counsel. He replied, Verify your quotations. – Sir Winston Churchill

But further, in order to embellish it with flowers of language and gems of thought, it is not necessary for this ornamentation to be spread evenly over the entire speech, but it must be so distributed that there may be brilliant jewels placed at various points as a sort of decoration. – Cicero, De oratore

The ancients, who in these matters were not perhaps such blockheads as some may conceive, considered poetical quotation as one of the requisite ornaments of oratory. – Isaac D’Israeli, “Quotation,” A Second Series of Curiosities of Literature