St. Ignatius Loyola is the founder of the religious order, known as the Jesuits. He was a noble knight. While recuperating from wounds, he had a religious conversion. The rest is history.
It was immediately after Ignatius' conversion that he was traveling to meet with his confreres regarding his new religious order. It's the sixteenth century; so his mode of transportation was a mule. While traveling, Ignatius met a man also riding on a mule. In the course of their brief conversation, the man insulted the Virgin Mary and then quickly took off. Now, mind you, Ignatius is still new in his religious conversion. His first reaction was to run the man through with his sword. But the man took off. He still wanted to chase him down and then kill him.
As he trotted or rambled, whatever mules do, Ignatius fumed. His good angel said let God handle the insult. His bad angel said murder was justified. Try as he might, he was unable to decide whether he should kill the man or not. At that moment he reached a (literal) fork in the road. Ignatius decided to leave the fate of the blasphemer up to his mule. As Ignatius wrote in his autobiography, "If the mule took the village road, I would seek him out and stab him; if the mule did not go toward the village, but took the highway, I would let him be." Fortunately for all concerned, the donkey chose the highway.
The moral of the story: "Ever since then, asses have been making decisions in the Jesuits."
Source: Between Heaven and Mirth: Why Joy, Humor, and Laughter Are at the Heart of the Spiritual Life by Fr. James Martin, s.j.