One of a group of radical Unitarian writers prominent in the 1860s and 1870s, John Weiss continued the work of Ralph Waldo Emerson and Theodore Parker well into a much-changed post-Civil War American society. He memorialized Parker in two volumes that are still read, and he wrote a challenging essay on his classmate Henry David Thoreau. But there was more to Weiss than a memorialist, for he was an original thinker about religion and science; he lectured widely on literary and historical topics, and he was an energetic advocate of social reform. A survey of his works reveals a man who was intellectually restless, probing, acerbic, and tenacious.

John Weiss was born on 28 June 1818 in Boston, the son of John and Mary (Galloupe) Weiss. His grandfather and great uncles were German political exiles, and his father was a barber. The family moved to Worcester and then sent John...