A Pythagoras Cup.

This is a Pythagoras or Greedy Cup. The cup is attributed to the Greek mathematician and philosopher Pythagoras. There is a line marked on the inside. If you fill with wine up to that line then all is fine. If you fill past the line the wine will drain out of the bottom leaving the cup empty and you with a wet lap!
As well as his fame as a mathematician, he is also celebrated for his philosophy and his way of life. The Pythagoras Cup illustrates a point that we should not ask for more than our share in life.