"as a Greek observed some two and a half thousand years ago"

Aristotle (384-322 BCE) was a Greek philosopher who wrote one of the first treatises of literary theory, the Poetics.  This book, only half of which has survived, covers the consituent elements, aims and style of poetry and an in-depth analysis of tragedy.  It has been an important resource for literary theory, although Aristotle's theories are still disputed.