Answer:
I am the book one can never finish reading
I am essential to life on earth! I am split into thirds. Two thirds are the same. One of the thirds is 8. The other two are 1 each.
I am the only vegetable or fruit that is never sold frozen canned processed or in any other form but fresh.
I need to be taken before you can have me. What am I?
What gets sharper the more you use it?
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.