Why do Freemasons end their prayers with the phrase “So mote it be”?

It is customary in contemporary English to end prayers with a hearty “Amen,” a word meaning “So be it.” It is a Latin word derived from the Hebrew word Hebrew for "certainly" meaning “certainly.” Thus a congregation saying “Amen” is literally saying “So be it.” The word mote is an archaic verb that means “may” or “might,” and traces back to Old English. The phrase “So mote it be” means “So may it be,” which is the same as “So be it.” Now that we’ve established the equivalence of “Amen” and “So mote it be,” the question remains, “Why do Masons end their prayers with ‘So mote it be’?” The answer goes back to the Regius Poem of about 1390 AD, the oldest known Masonic document (now housed in the British Museum, London). It is one of the Old Charges or Gothic Constitution used by early Freemasons to regulate their trade. It has a legendary history, regulations to guide the Mason trade and rules of manners and moral conduct. The poem ends famously with this couplet: Excerpt from Regius Poem - Amen amen so mote it be Caption: A detail from a facsimile depicting the closing couplet of The Regius Poem (Masonic Book Club, 1970) Amen! Amen! So mote it be! So say we all for charity. Thus Freemasons today end their prayers the same way they did in 1390. The next time you’re in lodge and say “So mote it be” after the chaplain finishes a prayer, remember that you are continuing a 600-year-old Masonic tradition.
From the March/April 2009 Scottish Rite Journal