The motto was Pax, but the word was set in a circle of thorns.
Source: On a Benedictine motto, In This House of Brede, Viking 69
-- Rumer Godden, (Dec 10 1907-1998), English novelist; She is a prolific writer of children's stories and adult fiction; six novels were adapted for films and TV, including In This House of Brede, 1975.