A Lion passed by a Field where four oxen lived. The lion tr...

A Lion passed by a Field where four oxen lived. The lion tried to attack them, but when he came near, the oxen turned their tails to one another for protection. So, every time the lion approached the oxen, he met the horns of one of them. The lion realized that those oxen were smart and went away.     But one day the oxen quarreled among themselves, and each one went to pasture alone in a separate corner of the field. Then the lion attacked them one by one and soon made an end to all four.
(ARSOP. The Four Oxen and the Lion. Available at: <www.australianstorytelling.org.au/txt/fables.php#52>. Access: Jun. 6,2014.)
That fable teaches us that _____.