Americans absolutely adore chocolate. The average American consumes 11 pounds of the stuff per year. But when did this love affair with chocolate start? Back in the 19th century, sugar was a luxury good, and chocolate was mostly for the rich. Milton Hershey, and his Hershey bar, changed all that. Historian Nancy Koehn, author of “Forged in Crisis: The Power of Courageous Leadership in Turbulent Times,” has written about Hershey’s life and company. She walks us through who he was, and how he gave America a taste for chocolate.