Answer:
Pregnant every time you see her, yet she never will give birth.
Scythe of darkness, Shadow’s light. Guiding eye of thirteenth sight.
My love, when I gaze on thy beautiful face. Careering along, yet always in place, the thought has often come into my mind. If I ever shall see thy glorious behind.
It comes only before, it comes only after. Rises only in darkness, but rises only in light. It is always the same, but is yet always different.
All about the house, with his lady he dances, yet he always works, and never romances.
You use it between your head and your toes, the more it works the thinner it grows.