J. Scott MacGregor, Lilly’s global communications director, declined to answer specific questions relating to this story. Although Lilly has vast archives, only scant evidence of those days remains outside the company’s headquarters. Antiques collectors have tinctures with the red-and-white Lilly label featuring cannabis sativa. But newspaper stories about those medicines and other accounts of them are scarce.

Making matters even stranger, one of Lilly’s most celebrated executives clearly had an interest in the subject. In 1907, the Philadelphia College of Pharmacy (the nation’s first pharmacy school) approved a doctoral thesis titled The Comparative Physiological Effects of Several Varieties of Cannabis Sativa. It tested five different strains of American cannabis against cannabis indica, which at the time was much more powerful. The student was none other than Eli Lilly, the grandson of Col. Eli Lilly, who went on to become the company’s third CEO.

In his quest to reveal Lilly’s history with cannabis, Pfenninger attempted to track down a copy of that document several times dating back nearly a decade. But an official at the college told him the thesis had been lost during a succession of three moves over the institution’s 200-year history. Recently, however, it turned up: An archives assistant at the J.W. England Library on campus found a photocopy. According to Andrew Peterson, a professor of clinical pharmacy at the college, it revealed groundbreaking research. “[Eli] was looking at it from a global perspective,” Peterson says. “It was cutting edge.”

Just as Lilly’s cannabis business ramped up, World War I closed naval shipping lanes and made importing the plant difficult. So in 1912, the corporation bought the farm in Greenfield. There, J.K. Lilly (the younger Eli’s brother and a president of the company himself) built a Spanish Mission–style building featuring stucco and red tile. Two years later, “Lilly Farms,” as the place was called, was up and running. The business figured out how to replicate the powerful Indian strain of marijuana. “Through advanced methods of seed selection and cultivation, Lilly Farms now produces cannabis of high potency, enabling us to offer a fluid extract equal to and identical with the therapeutic properties of the Indian cannabis,” according to Lilly’s January 1927 catalog A Complete Priced List of Products. For $6 per pint, you could get your hands on a tincture of cannabis sativa, a fifth of the price of cannabis indica, which retailed for $30. In the early 1900s, Lilly acquired what is now Conner Prairie, and went on to cultivate cannabis there as well, according to Don Wirtshafter, a marijuana historian and collector in Ohio. But in 1937, the Marijuana Tax Act, which placed a hefty tariff on the production of cannabis, made the operations money-losing propositions.

Political headwinds generated during the Prohibition era might have changed Lilly’s approach to the drug. A newspaper article in The Times of Gary headlined “Evil Is Growing Among Mexicans” summed up the shift in public opinion: “The Marijuana, or hasheesh smoking evil among Mexicans and negroes of Indiana Harbor is growing to an alarming extent with little or no chance of police intervention. Many of the recent crimes committed there by these races are differently traceable to the effect of this insidious weed.” Soon, Indiana had the most prohibitive laws against marijuana in the nation.

Long before the recent wave of medical marijuana legalization, Lilly was ahead of the curve as one of the world’s leading distributors of cannabis-based pharmaceuticals. But in 2019, they’d rather you not know it. All of which raises the question: Why?