Answer:
My first master has four legs, my second master has two. My first I serve in life, my second I serve in death. Tough I am, yet soft beside. Against ladies cheeks I often reside.
I turn around once. What is out will not get in. I turn around again. What is in will not get out.
There is an ancient invention. Still used in some parts of the world today. That allows people to see through walls.
What is so fragile that saying its name breaks it?
I never was, am always to be. No one ever saw me, nor ever will. And yet I am the confidence of all, To live and breath on this terrestrial ball.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?