February 24, 1208: Francis of Assisi experiences a vision in the church of Portunicula, Italy. Though not his first vision, it convinced him to begin a mission of preaching repentance, singing, caring for lepers, and aiding the peasants. Most notably, he and his followers renounced wealth and followed absolute poverty (see issue 42: Francis of Assisi).
February 24, 1582: Gregory XIII issues a bull requiring all Catholic countries to follow October 4 with October 15 and replace the Julian calendar with the Gregorian (which we still use today). By 1582, the Julian calendar had drifted from the equinoxes by a full ten days.
February 24, 1633: English poet and cleric George Herbert dies. His devotional poems, most of which are collected in The Temple, exemplify the metaphysical tradition (as do the poems of his contemporary John Donne).
July 18, 64: The Great Fire of Rome begins, and to direct suspicion away from himself, young Emperor Nero blames the city's Christians. A persecution followed in which Christians were (among other punishments) burned alive (see issue 27: Persecution in the Early Church).
July 18, 1504: Henry Bullinger, Ulrich Zwingli's successor as chief pastor of Zurich and a close associate of Cranmer, Melanchthon, Calvin, and Beza, is born in Switzerland (see issue 4: Ulrich Zwingli).