History is one of the three main genres in Western theatre alongside tragedy and comedy, although it originated, in its modern form, thousands of years later than the other primary genres. For this reason, it is often treated as a subset of tragedy. A play in this genre is known as a history play and is based on a historical narrative, often set in the medieval or early modern past. History emerged as a distinct genre from tragedy in Renaissance England. The best known examples of the genre are the history plays written by William Shakespeare, whose plays still serve to define the genre. History plays also appear elsewhere in British and Western literature, such as Thomas Heywood's Edward IV, Schiller's Mary Stuart or the Dutch play Gijsbrecht van Aemstel. Precursors Plays with some connection to historic narratives date to the beginnings of Athenian theatre. For one, although many early Greek plays covered subjects that modern audiences consider myth (rather than history), the Greeks did not make such a distinction, incorporating their stories of their gods into the same overarching narrative that included stories of their kings. Furthermore, the earliest surviving work of theatre, The Persians records an event that was entirely historical, even under the modern understanding of history. A key difference between The Persians and a history play in the modern sense is the incorporation of supernatural elements into the narrative of the Salamis. Additionally, it primarily dramatizes the Persian reaction to the battle, information that would have been at best a secondary concern for the Greek historian. Thus, although it concerns a verifiable historic event, it differs substantially from the modern genre of "history plays" in that it doesn't conform to the modern understanding of history (by presenting unvarifiable supernatural elements as fact) and in that its goals didn't entirely parallel those of ancient Greek historians. A significant development in the evolution of the history play occurred during the Middle Ages with the rise of mystery plays. Theatre in the Middle Ages arose from traditions surrounding the mass, a ritual that, due to the orthodox theological position that the eucharistic sacrifice reenacts (and even recreates) the sacrifice on the cross, has profound similarities to theatre (and to the types of rituals that gave rise to theatre in ancient Athens). While the regular Sunday liturgy was like theatre, the traditions that evolved around the Easter service were theatre.