In The Periodic Table, Primo Levi tells a story that happened when he was working in a varnish factory. He was a chemist, and he was fascinated by the fact that the varnish recipe included a raw onion. What could it be for? No one knew; it was just part of the recipe. So he investigated, and eventually discovered that they had started throwing the onion in years ago to test the temperature of the varnish: if it was hot enough, the onion would fry.
By the time Primo figured this out, modern thermometers rendered onions inessential. PG says that Arc will be the Lisp dialect that tries to avoid the onions. The inessential things that creep into our lives. How did they get there? We can't even remember.
This strikes me as a useful story for life. What are the onions in my varnish? Lets get rid of that stuff.