What Is Invention in Composition and Rhetoric?

"In classical rhetoric, invention is the first of the five canons of rhetoric: the discovery of the resources for persuasion inherent in any given rhetorical problem. Invention was known as heuresis in Greek, inventio in Latin."

In Cicero's early treatise De Inventione (c. 84 B.C.), the Roman philosopher and orator defined invention as the "discovery of valid or seemingly valid arguments to render one's cause probable."