Useless Things

I believe Edison's point was that failure is often a valuable lesson.

Or maybe that the “something “ that didn’t do what you planned may do something else that’s still useful. 

That's why I only order new gear from vendors that have 30 day return policies. It only becomes useless when it can't be returned.

Without looking up the exact quote, I'll paraphrase something else that he said.

"I didn't invent anything. I discovered a lot of things that didn't work."

A friend told a story about visiting another out of state friend, and noticed he was propping up his garage door for ventilation with a Mac amp chassis. My friend asked if he could go to Home Depot, pick up a concrete block to replace the the Mac amp as a door prop and take the Mac amp off his hands.. The friend agreed. It was a win/win.