Aristotle believed, unlike Plato, that art is imitation. Plato believed that art as imitation was bad because it failed on three different levels: epistemological, theological, and psychological. For Plato, imitation "removes reality," "represents gods in inappropriate ways," and "undermines stability."
Aristotle, on the other hand, believed in the power of imitation in art. For him, imitation is natural (learned young), and imitation is how behaviors are learned. Without imitation, some may not learn. Art, for Aristotle, allows for the wondrous in life to emerge.
Another aspect of art is its relation to catharsis. Catharsis refers to purification or purging. According to Aristotle, catharsis is important in art because it allows humans to move through the pain and come out cleansed on the "other side." Through the ability to remove one's self from the pain, he or she is able to reflect upon it and learn from it (tying the ideology back to the reasoning that art as imitation is good).