Answer:
Its title means book.
My teeth are sharp, my back is straight, to cut things up it is my fate.
The person who makes it has no need for it. The person who purchases it does not use it. The person who does use it does not know he or she is. What is it?
We are few to the wise; We are abundant to the drunken; We can calm the beast and are precious to the child; We can devour the heart, without piercing the skin
Although my cow is dead, I still beat her What a racket she makes.
You use it between your head and your toes, the more it works the thinner it grows.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?