The debate about pain perdu? Is the bread "lost" when you slip it into the custard to soak? Or does "perdu" refer to the state of your French toast bread, dry enough that it's "lost" or too old for the dinner table.
I've heard it both ways. But we can all agree on the rich, sweet flavor.
Americans tend toward challah or brioche for French toast, buying them specifically for making the sweet breakfast. But there's where a tradition is lost, for pain perdu evolved from the odds and ends left over from a week of eating bread at the table. In France, that most likely meant a pile of pieces from that week's baguettes.