 Early in his career, he painted portraits and landscapes of the Adirondack Mountain region of Lewis County, New York, his birthplace.He followed a self-prescribed educational path, begun by the Hudson River School and reinforced by John Ruskin's (1819–1900) truth-to-nature principles laid out in his book "Modern Painters".Although he can be allied to both schools of thought, Prentice can not be considered a member of either.