Ethos is a Greek word meaning 'character' that is used to describe the guiding beliefs or ideals that characterize a community, nation, or ideology; and the balance between caution, and passion. The Greeks also used this word to refer to the power of music to influence emotions, behaviors, and even morals. Early Greek stories of Orpheus exhibit this idea in a compelling way. The word's use in rhetoric is closely based on the Greek terminology used by Aristotle in his concept of the three artistic proofs or modes of persuasion alongside pathos and logos. It gives credit to the speaker, or the speaker is taking credit.

Aristotle's Poetics is the earliest surviving work of Greek dramatic theory and the first extant philosophical treatise to focus on literary theory. In this text Aristotle offers an account of ποιητική, which refers to poetry and more literally "the poetic art," deriving from the term for "poet; author; maker," ποιητής. Aristotle divides the art of poetry into verse drama, lyric poetry, and epic. The genres all share the function of mimesis, or imitation of life, but differ in three ways that Aristotle describes:Differences in music rhythm, harmony, meter, and melody. Difference of goodness in the characters. Difference in how the narrative is presented: telling a story or acting it out.