One of the reasons the Athenians poisoned Socrates was because he claimed to hear an inner voice, which he dubbed his daimonion, which told him what to do. Socrates believed that his daimonion was the true voice of God, and that everyone has access to these sorts of messages, if they only choose to listen.
In ancient Greece the dominant poetic form, epic, always begins with an invocation to the Muses, the nine daughters of Zeus and Mnemosyne, patronesses of the arts and literature. The poet would call upon these divinities to sing through them, to ignite their creative flames.
Today the word muse (ancient Greek: Μοῦσαι) has become somewhat problematic, as the millenia have enriched its meaning. You can still invoke the muses at the beginning of your long poem if you want to. But many also take muse to mean any person or object that “inspires” a work, be it a song, picture, or story. Additionally, it has acquired the connotation of the Socratic daimonion, an inner voice that leads the artist or poet down the paths of creation.
For my part, I find that all three are essential, for when present, the three divisions of human nature are present: the invocation is spiritual, the daimonion is of the mind, and the inspirational personage is or was incarnate, be they living or dead. This concept guides me in making decisions about who and what to photograph or write poems to or about.
Where identifying the human subject of a painting, drawing, photograph, poem, or song become problematic is when the humanity of the person goes unrecognized or is overlooked or forgotten. In this case, the muse ceases to be a complete person, and instead becomes an object or canvas onto which the artist may project their ideas.
Typically this objectification results in an imbalanced focus on the body, whereas superior work takes into account the entire person, even if one of the divisions is more heavily emphasized. Superior work is emblematic of something essential to humanity, and will always be something to strive for, something that will continue to inspire me until the day comes when I can work no more, (which will hopefully be the day I die).
I guess you might call that striving my muse.