Ida Tarbell was a muckraker, although she preferred to call herself a historian. Actually, she was both. And amazingly good at both callings. A fellow writer once said: "She was beautiful with virtue—so good, so modest, so full of kindness, and able to infect her pages with her own shining love of truth."

Muck is dirt. Muckrakers were journalists who wrote about wrongs: about injustice, unfairness, and corruption. They wrote about the mighty industrial tycoons, about how some of them broke the law and got away with it, and why that cost the public great sums of money. The muckrakers developed a new kind of journalism—investigative journalism—just at a time when improved publishing techniques made it possible to produce a magazine, distribute it widely, and sell it for ten cents. Everyone seemed to read the muckrakers' articles. That made them very influential. They helped bring about change. Ida Tarbell was the most famous. A colleague, the progressive journalist Lincoln Steffens, once described her: "Sensible, capable, and very affectionate, she knew all our idiosyncrasies and troubles. She had none of her own so far as I ever heard."

When Ida Tarbell was a girl, she wished to be a scientist. She soon discovered that a degree and a passion for science were not enough: scientific research, like most fields, was a men-only domain. Ida became a teacher, but found she didn't really want to teach, so she went off to France. She had a little money and a lot of adventurousness, and she could write. That was what she was doing when Samuel McClure walked into her life.