See O. W. Holmes, John Lothrop Motley: A Memoir (1879); G. W. Curtis, ed., The Correspondence of John Lothrop Motley (1889); John Lothrop Motley and His Family (ed. by his daughter, Susan M. Mildmay, and H. S. Mildmay, 1910).
Motley refers to the traditional costume of the court jester or the harlequin character in commedia dell'arte. The latter wears a patchwork of red, green and blue diamonds that is still a fashion motif.
The word motley is described in the Oxford English Dictionary as a cognate with medley, although the unrelated mottled has also contributed to the meaning. The word is most commonly used as an adjective or noun, but is also seen as a verb and adverb. When used as a noun, it can mean "a varied mixture."
The word originated in England between the 14th and 17th centuries and referred to a woolen fabric of mixed colors. It was the characteristic dress of the professional fool. During the reign of Elizabeth I, motley served the important purpose of keeping the fool outside the social hierarchy and therefore not subject to class distinction. Since the fool was outside the dress laws (sumptuary law), the fool was able to speak more freely.
Likewise, motley did not have to be checkered and has been recently thought to be one pattern with different colored threads running through it.