One day a merchant loaded his donkey with sacks of salt and went to the market. There was a river on their way. The donkey's job was hard! The poor creature slipped down and fell into the water. When he recovered his feet, his load was much lighter! The salt had dissolved in the water!
Some days passed. The merchant loaded the donkey with sacks again and went to the market. As soon as they reached the river, the donkey went and fell into the water on purpose. Then he alighted on his feet just as if nothing had happened.
The master put two and two together, got angry and thought: "All right, you, rotten brute! I'll show you what is what!" When they went to the market again the stupid animal fell into the water laughing in his beard. But when he wanted to recover his feet, it turned out that the sacks were even heavier! He barely got out of the water. How could he know that cotton had taken up the water!
And the master is looking at the donkey and gloating:
"It serves you right! Don't play the fox!"

Electronic text: Moshkov Library

These two characters used not so much inventive principles as the knowledge of physical effects. The donkey: Water dissolves salt (the knowledge was obtained empirically). The master: Cotton absorbs water (the experience of the previous generations).