Metaphor is one of the most important entries in Rhetoric, at least in the classic meaning of the term. Today its most accepted definition, a trope indicating similarity, is the outcome of the efforts of great men such as Abdol Ghader Jorjani and Abu Yaghub Sakaki, who introduced and developed this theory in Islamic Rhetoric. Jorjani's theory of metaphor, which is the result of his deep investigation in the works of the ancient scholars and writers, shows a functionalist insight in to metaphor. The scholars of eloquence, Jorjan being the last in their chain, had a particular attention to the holy Quran in their study of rhetoric, which made them see that linguistic segments play an important role in reading the verses of the Quran. In his book, Miftah Al-Ulum, Sakaki, who followed Jorjani's theory, gives the theory another interpretation. While Jorjani had a deep insight in to the role of linguistic segments, Sakaki's literature-based view leads him to ignore the necessity of considering the function in metaphor. Comparing the views of these two theorists reveals that they have different ideas, not only regarding this issue but concerning so many other issues. The present study aims to investigate these differences and endeavours to show the differences of these two scholars on the definition and nature of metaphor and the way it should be treated