Hephaestion (Ancient Greek: Ἡφαιστίων Hēphaistíōn; fl. 2nd century AD) was a grammarian of Alexandria who flourished in the age of the Antonines. He was the author of a manual (abridged from a larger work in 48 books) of Greek metres, which is most valuable as the only complete treatise on the subject that has been preserved. The concluding chapter discusses the various kinds of poetical composition. It is written in a clear and simple style, and was much used as a school-book. Source: Wikipedia (en)