He was born in Haverhill, New Hampshire to Edward Clark and Elizabeth Weston, but the family soon relocated to Peacham, Vermont where he grew up. Decades after his death, "The Friend" periodical put together his biography based on unpublished writings he had begun during the last year of his life. In his notes, Clark had described his father as a soldier with the Marquis de Lafayette during the Siege of Yorktown, and his mother's father Ephraim Weston as a soldier in the "French War of 1775" (possibly referring to the Siege of Fort St. Jean).