Aristotle writes in his "Poetics" that epic poetry, tragedy, comedy, dithyrambic poetry, painting, sculpture, music, and dance are all fundamentally acts of "mimesis" ("imitation"), each varying in imitation by medium, object, and manner. He applies the term "mimesis" both as a property of a work of art and also as the product of the artist's intention and contends that the audience's realisation of the "mimesis" is vital to understanding the work itself. Aristotle states that "mimesis" is a natural instinct of humanity that separates humans from animals and that all human artistry "follows the pattern of nature". Because of this, Aristotle believed that each of the mimetic arts possesses what Stephen Halliwell calls "highly structured procedures for the achievement of their purposes." For example, music imitates with the media of rhythm and harmony, whereas dance imitates with rhythm alone, and poetry with language. The forms also differ in their object of imitation. Comedy, for instance, is a dramatic imitation of men worse than average; whereas tragedy imitates men slightly better than average. Lastly, the forms differ in their manner of imitation – through narrative or character, through change or no change, and through drama or no drama.