John Davison Rockefeller arguably ranks as the most wealthy man ever — his cashbox stuffed with about $330 billion in today’s dollars.

Every few years, Business Insider or Forbes line up their lists of the richest individuals in history. Almost invariably, a grim Rockefeller stares down from the top of the heap, keeping the pile down with one sharp heel wedged against Andrew Carnegie’s forehead and the other dug into Henry Ford’s back.

The future king of oil was born into a relatively poor New York family in 1839 — and even as a child was driven by numbers, barter, turning a buck and riches. As a boy, Rockefeller played prophet to his own wealth; he firmly believed it was of a matter of when, not if.

At 16, living in Cleveland, Ohio, Rockefeller got his start. Legend has it he knocked on the door of every commodity house in Cleveland and asked for a job. Door-knocking legend or not, a small produce firm, Hewitt & Tuttle, took a chance on an odd young man: “Watch and learn, son. Watch and learn.”

Over four years, Rockefeller manned the ledger books, crunching numbers and studying the trade in agricultural commodities. By 1859 (same year a major oil extraction advance was made in nearby Titusvillle, Pa.), aged 20, he was ready for the commodity trade — as proprietor and not pupil. Along with a partner, and a $4,000 stake, Clark & Rockefeller was in the commodities game. Rockefeller layered success on top of success and drove his new firm from strength to strength.

Had it not been for the merger of history and oil, Rockefeller probably would have found success as a wheat or corn king and been a titan in agricultural history. As oil extraction was perfected and refineries went up almost overnight, the business world was still skittish, afraid that the oil craze might pass quickly. As the seasoned veterans of industry stood around the oil pool edges and dangled a toe — Rockefeller leaped right in. They were leery; he was sure. They were wrong and he was right — Standard Oil was soon born.

Those same veterans would soon be swallowed by Rockefeller’s monopoly. His Baptist sensibilities took a quick backseat in dealings with competitors. Moralist and magnate, Rockefeller died at age 97. Despite his storybook wealth, the richest man in history was once a young fellow who cut his business teeth on grain, hay and meats — agricultural commodities.