Answer:
What is so delicate that saying its name breaks it?
I love spinach.
Adored by few, feared and hated by many. Mistress of the entire universal reason, master in the art of numbers. Some may have solved many of my mysteries, but there are still many of them to find. What am I?
I hide but my head is outside. What am I?
You write on me and secrets I can keep in places never seen. I spin like a top. Though stiff as a board, I'm often described like a mop. What am I?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?