Even today, sources on inventions list six by Franklin that are still in active use today. One of those sits in my back hall, cheerfully and economically heating the back of my home – the Franklin stove. Another sits on the bridge of my nose as I write this – a pair of bifocals. But this is about Franklin’s greatest invention, one that the lists never mention because it is mere words, not a physical object. Franklin made seven trips to Europe, as a diplomat and scholar. He was welcomed into all the learned societies that existed in Europe then....