Twenty-six years old, and left by his father’s death to run the family farm here in the rich soil of the Arkansas Delta, John Henry penciled out his problem this way: 1,000 acres planted with soybeans, each producing 40 bushels, equaled 40,000 bushels of soybeans. What to do with all those soybeans? Henry’s pursuit of a solution led him to the commodity markets, where contracts for agricultural products are bought and sold, and sparked a fascination with price movements that ultimately transformed him from farmer to financier. In less than a decade, Henry, a college dropout, not only taught himself the risky business of commodity speculation, but in short order devised his still-working trading model; pioneered a type of investment called “managed futures”; and launched a firm that is among the most successful of its kind in the world.