Cup of Pythagoras

The Pythagorean cup – also known as the cup of moderation or Tantalus cup – is a drinking vessel that forces the user to drink moderately.

Thanks to its clever design, the cup can only be filled to a certain height. This allows the modest user to enjoy their drink in peace. However, if they are greedy and pour above the fill line, the entire contents will empty onto the drinker's lap.

It is said that Pythagoras used this cup to teach his wine-drinking workers moderation.