ABSTRACT
Imagine that you are an expert in making chains, and that you are working on a project to suspend a box containing delicate porcelain high above ground. If the chain, the box, the hook that attaches the chain to the box, or the hook that attaches the chain to the ceiling breaks, the box will fall and hit the ground. Clearly, serious damage to the porcelain will probably result. Everybody involved with the porcelain (the owner of the porcelain, the expert in boxes, the expert in hooks, you, etc.) would like to prevent that.
