Answer:
An utensil used for bread. Also a paper cutter. Used by a thug to take a life, Or wielded by the tamest wife, When used to spread the butter.
What has no hands but might knock on your door, and if it does you better open up?
What is part of you and all around you but if it entangles you, it will kill you?
Proof you've done your time in school
I go around in circles, But always straight ahead Never complain, No matter where I am led.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.