Pentalogy - Plotinus, Porphyry (Philosopher), Perfect Number

A pentalogy is a compound literary or narrative work that is made up of five (numerical prefix penta-) distinct works, just as a trilogy is made up of three works, and a tetralogy of four. Although use of the word might seem to imply that the structure was intended by the author, historically, a pentalogia could be assembled by a later editor, just as Plotinus's Enneads were arranged in nines by Porphyry in order to create an overarching structure of six which would express the idea of perfection.