Martyrdom of St. Boniface among the Frisians; when they swung a sword at his head, he held up a Gospel codex as a shield; the book was cut through the middle but not a single letter was destroyed
"when in the year of the Lord 755 the Frisians swung a sword at his head, he held up this codex as a spiritual shield, and by a remarkable miracle, although the book was cut through the middle by the sharp sword, nevertheless not a single letter was destroyed by that cut."