Not far from Walden Pond, where Henry David Thoreau lived for two years in a cabin he built along its shore, sits a solitary stone that tells a story about another man. It’s a story that many have never heard, even though Thoreau himself wrote about it, though briefly. The stone commemorates the life of Brister Freeman. Brister Freeman was born Brister Cuming in Concord around 1744 and spent roughly the first 25 to 30 years of his life as an enslaved man to Dr. John Cuming. In 1777, he served…