The Ass and His Burdens explained simply

A Pedlar who owned an Ass one day bought a quantity of salt, and loaded up his beast with as much as he could bear. On the way home the Ass stumbled as he was crossing a stream and fell into the water. The salt got thoroughly wetted and much of it melted and drained away, so that, when he got on his legs again, the Ass found his load had become much less heavy. His master, however, drove him back to town and bought more salt, which he added to what remained in the panniers, and started out again. No sooner had they reached a stream than the Ass lay down in it, and rose, as before, with a much lighter load. But his master detected the trick, and turning back once more, bought a large number of sponges, and piled them on the back of the Ass. When they came to the stream the Ass again lay down: but this time, as the sponges soaked up large quantities of water, he found, when he got up on his legs, that he had a bigger burden to carry than ever. You may play a good card once too often.