As a mail carrier in rural Grand Rapids, Minn., for 35 years, John Latimer put his own stamp on a career that delivered more than letters. Indeed, while driving the hundred-mile round-trip daily route, he passed the time by observing and recording seasonal changes in nature, learning everything he could about the area’s weather, plants and animals, and becoming the go-to guy who could answer customers’ questions about what they were seeing in the environment.