In the Middle Ages a guild of masons specially employed in building churches. Called “free” because exempted by several papal bulls from the laws which bore upon common craftsmen, and exempt from the burdens thrown on the working classes.
St. Paul's, London, in 604, and St. Peter's, Westminster, in 605, were built by Freemasons. Gundulph (bishop of Rochester), who built the White Tower, was a “Grand Master;” so was Peter of Colechurch, architect of Old London Bridge. Henry VII.'s chapel, Westminster, was the work of a Master Mason; so were Sir Thomas Gresham (who planned the Royal Exchange), Inigo Jones, and Sir Christopher Wren. Covent Garden theatre was founded in 1808 by the Prince of Wales in his capacity of “Grand Master.”
“Before the beginning of the 13th century the corporation of freemasons was not sufficiently organised to have had much influence on art.” —J. Fergusson: Historic Archaeology, vol. i. part ii. chap. viii. p. 527.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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