Electricity was on people's minds in the 1740s, but not in the way we think about it today. People used electricity for magic tricks by creating sparks and shocks. Scientists conducted experiments with electricity, but scientific thinking about electricity had not changed much in hundreds of years. Electricity wasn't "useful" yet.
Benjamin Franklin was interested in electricity. Being a curious and inventive thinker, Franklin wanted to know more than just the popular tricks. He kept thinking about electricity and came up with a very important idea.