The classical text reproduced below is important for three reasons: it was written by James Sully, one of Britain's most outstanding 19th-century philosophers and psychologists; it makes an interesting distinction between the concepts of illusion and fallacy; and it contains a veiled warning as to the efficiency of the epistemological method of psychological introspection. Each of these points is dealt with briefly in this introduction.
James Sully; illusion; fallacy; introspection