The father and his sons

by Aesop

 A certain man had several sons who were always quarreling with one another, and, try as he might, he could not get them to live together in harmony. So he determined to convince them of their folly by the following means. Bidding them fetch a bundle of sticks, he invited each in turn to break it across his knee. All tried and all failed: and then he undid the bundle, and handed them the sticks one by one, when they had no difficulty at all in breaking them. "There, my boys," said he, "united you will be more than a match for your enemies: but if you quarrel and separate, your weakness will put you at the mercy of those who attack you."

Union is strength.