Thomas Aquinas, who was inspired with Aristotle’s philosophy in developing some of his views, followed his path in considering art as a kind of imitation. However, the concept of imitation for him was not a purely Aristotelian one; rather, it was also influenced by the viewpoints of some thinkers such as Augustine and Pseudo-Dionysios the Areopagite. He employed mimesis in the texture of Christian theological discussions as well as in relation to the issues related to the metaphorical language of holy texts. Therefore, the concept of mimesis in Aquinas’ view was faced with an epistemological dilemma. On the one hand, it could result in both anxiety and relaxation in addressees or perhaps, through affecting their imagination, distract them from the path of rationality. On the other hand, it seems that the language of the Holy Book, which has been written for leading its addressees to the path of intellection and religiosity, shares the same features of the language of artistic works. Different types of mimesis have been used in the Holy Book and, more importantly, the relationship between the world of being and God is explained there on the basis of the concept of mimesis or imitation. In this paper, through analyzing the views of Aquinas and his references to such philosophers as Aristotle, Augustine, and Pseudo-Dionysius the Areopagite, the authors try to provide a clear explanation of the concept of mimesis and the epistemological functions of artistic imitation in Thomism.