carry coals, put up with insults. A phrase very common in the old dramatists and owing its origin to the fact that the carriers of coals were the lowest of menials. Cp. e.g. H.V. iii.2.49, "Nym and Bardolph are sworn brothers in filching, and in Calais they stole a fire-shovel: I knew by that piece of service
the men would carry coals"; Jonson, Every Man Out of His Humour, v.1.18,9, "here comes one that will carry coals, ergo, will hold my dog"; Chapman, May Day, iii., speaks of "an uncole-carrying spirit." From the same source we have the word blackguard as a term of abuse, it being originally applied to "the
smutty regiment," as Gifford calls them, "who attended the [sovereign's] progresses, and rode with the pots and kettles, which, with every other article of furniture, were then moved from
palace to palace" ... .
Shakespeare, William. Romeo and Juliet. Ed. K. Deighton. New York: MacMillan and Co., 1903. Shakespeare Online. 20 Aug. 2010. (date when you accessed the information) < http://www.shakespeare-online.com/plays/romeoglosscoals_1_1.html >.