Aesop
The Ass and the Mule
A MULETEER set forth on a journey, driving before him an Ass and
a Mule, both well laden. The Ass, as long as he traveled along
the plain, carried his load with ease, but when he began to
ascend the steep path of the mountain, felt his load to be more
than he could bear. He entreated his companion to relieve him of
a small portion, that he might carry home the rest; but the Mule
paid no attention to the request. The Ass shortly afterwards
fell down dead under his burden. Not knowing what else to do in
so wild a region, the Muleteer placed upon the Mule the load
carried by the Ass in addition to his own, and at the top of all
placed the hide of the Ass, after he had skinned him. The Mule,
groaning beneath his heavy burden, said to himself: "I am treated
according to my deserts. If I had only been willing to assist
the Ass a little in his need, I should not now be bearing,
together with his burden, himself as well."

"An ounce of prevention is worth a pound of cure"