In Greek mythology the Muses are a sisterhood of goddesses or
spirits, their number set at nine by Classical times, who embody
the arts and inspire the creation process with their graces and
beauty. They were water nymphs associated with the springs
of Helicon and with the Pieris, and as a consequence they are
sometimes called the Pierides.
Apollo, God of War, was their leader.
Not only are the Muses explicitly
used in modern English to refer to an inspiration,
they are also implicit in the words
"amuse" or "musing upon."
The Muse is dead. Long live the Muse.