The glass protects the artifact while making its old usefulness impossible to experience.

Preservation and use pull in opposite directions. A tool behind glass will last another century and will never again be picked up, balanced, or found heavier than it looks, which is where most of its meaning lived. The display keeps the object and loses the verb. Every act of protection trades something away, often the thing that made it worth protecting.

When you look at something in a case, imagine its weight and the hand that used it. In your own life, ask whether anything you are keeping safe is being kept out of use altogether.