Saint Thomas Aquinas (1225-1274)
Give me, O Lord, an ever watchful heart which no subtle speculation may ever lure from you. Give me a noble heart that no unworthy affection shall ever draw downwards to earth. Give me a heart of honesty that no insincerity shall warp. Give me a heart of courage that no distress shall ever crush or quench. Give me a heart so free that no perverted or impetuous affection shall ever claim it for its own.