What Is The Moral Of The Fable "The Donkey And The Shadow"?

A traveller wanted to cross the desert. He paid a nomad, who knew the desert very well, to guide him; and also hired the nomad's donkey, to carry his gear.

They walked along for several hours. The nomad was comfortable in the heat, but the traveller eventually got very tired and asked for a rest. They sat down in the sand; and the traveller lay down in the shade provided by the donkey and fell asleep.

After a while the nomad also began to feel uncomfortable. He watched the sleeping man and felt annoyed; after all, it was his donkey. He took the animal's bridle and moved it forward a few paces, so that he could lie in the shade instead. This woke the traveller, who angrily claimed that, having hired the donkey, he had a right to use its shadow too. The nomad claimed that he had not rented the shadow, but only the animal. The noise of their quarrel frightened the donkey, which ran away.

So in quarrelling over the shadow, they lost the substance.