Unlike ancient rhetoricians who rejected ambiguity altogether, modern theorists consider it as a value. This article, initially, presents a historical survey as well as the modern approaches to ambiguity and highlights the modern aesthetic tendency toward ambiguity and polysemy. After the early years of 20^th century, ambiguity was considered as the essential essence of literary texts by literary critics and theorists. Second, the article discusses the value of ambiguity in literary works and draws a borderline between difficulty and polysemy (i.e. pluralization and multiple meaning). Then, it introduces some kinds of ambiguity and elaborates on their distinct features. Meanwhile, this article pinpoints the basic deference between language and literature through emphasizing the value and function of ambiguity.  The main purpose of the article, then, is to emphasis that "ambiguity as inherent nature of literature" and stresses the principle saying: "the artistic value of a literary work and the secret of its eternality depend on the amount of its ambiguity". If one ignores the ambiguity in literary texts, he would lose its spirit and essential essence. Ambiguity causes an interaction between   reader and text and fosters the ability of meaning creation by readers.  Through persuading the readers to react to the content of text, ambiguity provides the opportunities for generations to engage in different dialogues with text across time and history.