Aesop's Fables
#108 The Fly and the Draught-Mule
A Fly sat on the axle-tree of a chariot, and addressing the Draught-Mule said, "How slow you are! Why do you not go faster? See if I do not prick your neck with my sting."
The Draught-Mule replied, "I do not heed your threats; I only care for him who sits above you, and who quickens my pace with his whip, or holds me back with the reins. Away, therefore, with your insolence, for I know well when to go fast, and when to go slow."