The answer is that he was extremely curious. Ben couldn’t help wondering why things did whatever they did or trying to figure out how things worked. Ben noticed that gypsum (a chalklike substance found naturally in rocks) spread on a field made grass grow greener. He suggested farmers put it on their crops. As a result, he’s credited with the idea of using artificial fertilizer. He was also one of the first to realize that lead poisoning was the reason so many printers, painters, and plumbers were getting sick.