Muse
a:A guiding spirit.
b:A source of inspiration.
\Muse\, n. [F. Muse, L. Musa, Gr. ?. Cf. Mosaic, n., Music.] 1. (Class. Myth.) One of the nine goddesses who presided over song and the different kinds of poetry, and also the arts and sciences; -- often used in the plural.
v. mused, mus·ing, mus·es v. intr.
To be absorbed in one's thoughts; engage in meditation.

Calliope - The Muse of epic poetry.
Clio - The Muse of history.
Erato -The Muse of lyric poetry and mime.
Euterpe - The Muse of lyric poetry and music.
Melpomene - The Muse of tragedy.
Polyhymnia - The Muse of sacred song and oratory.
Terpsichore - The Muse of dancing and choral singing.
Thalia - The Muse of comedy and pastoral poetry.
One of the three Graces.
Urania - The muse of astronomy.