St. Justin, apologist and martyr, was one of the most important Christian writers of the second century. He himself tells how his study of all the schools of philosophy led him to Christianity and how he dedicated his life to the defense of the Christian faith as “the one certain and profitable philosophy.” St. Justin is particularly celebrated for the two Apologies which he was courageous enough to address in succession to the persecuting emperors Antoninus and Marcus Aurelius. One of them contains a description of the rites of baptism and the ceremonies of Mass, thus constituting the most valuable evidence that we possess on the Roman liturgy of his day. He was beheaded in Rome in 165.