<human>:  Why does the Phantom have a mask in the musical ‘The Phantom of the Opera’?
<bot>: The Phantom has a mask because he is a phantom, and he is a phantom of the opera. The Phantom is a character from the musical Phantom of the Opera. The Phantom is a mysterious character who appears in the opera and performs a number of strange acts, like killing people and throwing them into the river. He is a tragic figure, and he wears a mask to hide his identity.