At 50, Mr. Moore and his wife moved to Portland, Oregon. He had dreamed of going to seminary. He longed to master Hebrew and Greek so he could read the Bible in its original languages.

One day, he and his wife were walking as they studied Greek nouns and verbs. Mr. Moore looked up—and spotted an old mill. There was a “For Sale” sign out front. Mr. Moore couldn’t believe it. The dream that had started back in the library reared to life again. The owner planned to tear down the mill and sell the land.

Mr. Moore bought the mill. He says that choice changed his entire life.

Starting Bob’s Red Mill in 1978 wasn’t easy, but the Moores were used to challenge. (Decades earlier, they had bought a gas station that failed.) Their new company supplied food to people in the Pacific Northwest for 10 years. Then a fire destroyed it. Instead of giving up, the Moores moved into a plant three times larger. Soon, the company supplied goods to buyers across the country. Now Bob’s Red Mill markets more than 200 products in more than 70 countries.

Mr. Moore was famous for his folksy style, red vest, newsie caps, and small-town pace. He used older machines, complaining that others “screamed, got hot, and went 94 miles per hour. I don’t live my life that way, and I don’t want my food that way.”

But his greatest claim to fame is his generosity. Mr. Moore turned 81 in 2010. That year, he started giving his staff some control and profits of the business. He didn’t hoard his wealth. He shared it. He explained to Portland Monthly: “The Bible says to do unto others as you would have them do unto you.”