From what two instincts "natural to human beings" does poetry, according to Aristotle, seem to have sprung?

In the Poetics, Aristotle argues that the impulse to poetry is universal, rather than grounded in particular cultural circumstances. In fact, for Aristotle, the universality of poetry and its grounding in universal instincts are what makes it more valuable and in a sense truer than history, as history tells of what is local and specific and poetry of universal truths about human nature.

The first of the two instincts Aristotle discusses is the instinct for imitation. Even young children enjoy and engage in forms of mimicry, and humans universally seem to find imitation (Greek: mimesis) pleasurable.

The second instinct that Aristotle notes is that for rhythm and harmony. All societies seem to enjoy some forms of music. It is important in the context to remember that Aristotle is discussing ancient Greek poetry, which was performed with musical accompaniment, unlike modern poetry which is normally read privately and silently rather than heard.