1026. The sun set. Thomas and his wife went to bed. He said, "I'm tired of going to bed at sunset. I'm going to invent a light bulb. It'll attach to a lamp with an on‐off switch and a cord. The cord will contain copper wires that connect to a plug that goes into a wall socket. The socket has wires that connect to a source of electricity. At sunset, we'll turn on the lamp and voila—light!" Mary said, "That's nice, dear. But what is 'electricity,' and where does it come from?" He said, "Well, electricity is energy. But I'm still working on exactly where it's going to come from." She said, "Well, can I suggest something? I don't think people will like having ugly wires all over their house." He said, "Trust me. People will be so thrilled with electricity, they'll never give a second thought to the wires." 3.4