The muses were nine goddesses, daughters of Zeus, regarded as presiding over and inspiring learning and the arts, esp. poetry and music.1
Experiencing burn out at many points in my life, I often find the first signal of it is when I long for that inspiration, that energy that makes you produce something in which the process of creating totally blinkers you from the rest of the world. The feeling is indescribable, you’ll look at your clock at 4am and realise that you’ve not had dinner. When I start burning out I lose the ability to do that.
I’m currently on, as probably many attempt, a mission to try and foster this feeling and target it usefully.