It is well documented that Moses Ibn Ezra and the prominent philosopher Moses ben Maimon - Maimonides - had different opinions as to what represented a metaphor. Both philosophers had a huge impact on the use of metaphors in literary texts. Within the "Kitab", Ibn Ezra attempted to use both Arabic and Hebrew forms of metaphor with passages taken from both the Qur'an and Bible. Ibn Ezra was quite critical of earlier authors who used metaphor only to exaggerate or substituted metaphor for precise literal language. Ibn Ezra's definition of metaphor revolves around the meaning of "isti-ara" (borrowing), which is a word meaning something not known using something already known. This is Ibn Ezra's way of explaining the concept of God and God's existence. Maimonides similarly defines metaphor as temporarily “borrowing.” Maimonides’ source for his definition of metaphor is from al-Farabi's "Short Treatise" on Aristotle's "De Interpretatione". This model defines metaphor as "saying X and really meaning Y"; hence, the claim "X is a metaphor" entails proving that it refers to Y and not to X. One of his criticisms of Ibn Ezra was that Ibn Ezra simply cited his forty biblical examples without elucidation, even though many of them are not readily referenced. The fact that these two philosophers differed so greatly is not much of a surprise since their agendas also differed. Ibn Ezra was predominantly interested in the poetic aspect of metaphor whereas Maimonides had a pure philosophical intent in his definition.