Study of making prostheses in discourse; why does narrative lie make prostheses?

To explain how lie functions as prosthesis, first we need to define prosthesis and its function in the domain of discourse. According to Eco's theory of prosthesis and its function in discourse, We show that lie as a discourse has common characteristics with prosthesis. This article examines how discourse functions as prosthesis and as a result lie as a prosthesis makes the exit of discourse out of its mainstream and creates an event and imaginary space which is meta-action. According to the above mentioned matters, these two hypotheses will be studied; discourse with the use of lie changes horizontal system of story to vertical system and as a result, the action plan change into a meta-action one. This survey has been done in three folk tales; the crow and fox, boy who cried wolf and the milk seller girl and milk jug.