Galvani himself thought this had something to do with the leg, and not with the metal tools he used. Volta saw that the tools "must" be made from two "different" metals for the leg to move. Volta also found that he could make a little electricity just by making two different metals touch each other. He thought that the two different metals gave something he called "contact tension", and the electricity came from that contact tension. Galvani and Volta talked a lot about this, but they never agreed.