Draw a snake and add feet to it -- Ruin the effect by adding something superfluous

An official of the ancient State of Chu during the Spring & Autumn and Warring States Period (770-221BC) awarded a pot of wine to his men after the ceremony of Spring Sacrifice. One man said, "We have only one pot of wine. It's not enough for all of us but sufficient for one. Let's determine who'll have the wine by drawing a snake on the ground. He who finishes first will have the wine."

The others agreed. Very soon, one man finished his snake. He was about to drink the wine when he saw the others were still busy drawing. He said complacently,"How slowly you are! I still have enough time to add feet to my snake." But before he finished the feet, another man finished his snake and grabbed the pot from him, saying, "Whoever has seen a snake with feet? Yours is not a snake. So the wine should be mine!" He drank the wine. The man adding the feet to the snake had to give in and could only regret his foolishness.

From that story comes the idiom -- Draw a snake and add feet to it. Now people use this idiom to illustrate the truth that going too far is as bad as not going far enough. It somewhat like the English saying: Too much water drowned the miller.