E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
for mourning was a Roman custom (Juvenal, x. 245) borrowed from the Egyptians.
Black, in blazonry, means constancy, wisdom, and prudence.
Black, in several of the Oriental nations, is a badge of servitude, slavery, and low birth. Our word blackguard seems to point to this meaning. The Latin niger meant bad, unpropitious. (See BLACKGUARD.)