After the king dies, two men, the true heir and an impostor, both claim to be his long-lost son. Both fit the description of the rightful heir: about the right age, height, coloring and general appearance. Finally, one of the elders proposes a test to identify the true heir. One man agrees to the test while the other flatly refuses. The one who agreed is immediately sent on his way, and the one who refused is correctly identified as the rightful heir. Can you figure out why?