One day a friend of St. Thomas of Aquinas cried out to him by way of amusement: “Thomas, look at the flying ox.” St. Thomas looked around him in astonishment to see where the strange animal was, but of course could not see it anywhere. His friend then began to laugh, and said to him that he was surprised to see that he was so credulous. But the Saint replied: “It is much easier to believe that an ox could fly than that a Catholic could tell a lie.”
Stories From The Catechist by Very Rev. Canon G.E. Howe, Pg. 271 #633.
Short Stories on Honor, Chivalry, and the World of Nobility—no. 480