Only seven of his estimated seventy to ninety plays have survived. There is a long-standing debate regarding the authorship of one of these plays, "Prometheus Bound". Some believe that his son Euphorion wrote it. Fragments from other of Aeschylus' plays have survived in quotations, and more continue to be discovered on Egyptian papyrus. These fragments often give further insights into Aeschylus' work. He was probably the first dramatist to present plays as a trilogy. His "Oresteia" is the only extant and ancient example. At least one of his plays was influenced by the Persians' second invasion of Greece (480–479 BC). This work, "The Persians", is one of very few classical Greek tragedies concerned with contemporary events, and the only one extant. The significance of the war against Persia was so great to Aeschylus and the Greeks that Aeschylus' epitaph commemorates his participation in the Greek victory at Marathon while making no mention of his success as a playwright. Despite this, Aeschylus's work – particularly the "Oresteia" "–" is generally acclaimed by modern critics and scholars.