Campbell relied heavily on a book written by physician David Hartley , entitled Observations on Man .
George Campbell , a contributor to the Scottish Enlightenment , was one of the first rhetoricians to incorporate scientific evidence into his theory of emotional appeal .
one relied heavily on a book written by physician David Hartley , entitled Observations on Man .
George Campbell , a contributor to the Scottish Enlightenment , was one of the first rhetoricians to incorporate scientific evidence into his theory of emotional appeal .