that generate madness, ruination, and self-destruction. This has a cosmic as well as an ethical aspect, and fate is a powerful, albeit rather oppressive, force. Many scholars have thought, following the ideas of the 19th-century German scholar Friedrich Leo, that Seneca's tragedies were written for recitation only. Other scholars think that they were written for performance and that it is possible that actual performance took place in Seneca's lifetime. Ultimately, this issue cannot be resolved on the basis of our existing knowledge. The tragedies of Seneca have been successfully staged in modern times. The dating of the tragedies is highly problematic in the absence of any ancient references. A parody of a lament from Hercules Furens appears in the Apocolocyntosis, which implies a date before 54 AD for that play. A relative chronology has been proposed on metrical grounds. The plays are not all based on the Greek pattern; they have a five-act form and differ in many respects from extant Attic drama, and while the influence of Euripides on some of these works is considerable, so is the influence of Virgil and Ovid. Seneca's plays were widely read in medieval and Renaissance European universities and strongly influenced tragic drama in that time, such as Elizabethan England (William Shakespeare and other playwrights), France (Corneille and Racine), and the Netherlands (Joost van den Vondel). English translations of Seneca's tragedies appeared in print in the mid-16th century, with all ten published collectively in 1581. He is regarded as the source and inspiration for what is known as "Revenge Tragedy", starting with Thomas Kyd's The Spanish Tragedy and continuing well into the Jacobean era. Thyestes is considered Seneca's masterpiece, and has been described by scholar Dana Gioia as "one of the most influential plays ever written". Medea is also highly regarded, and was praised along with Phaedra by T. S. Eliot. Works Works attributed to Seneca include 12 philosophical essays, 124 letters dealing with moral issues, nine tragedies, and a satire, the attribution of which is disputed. His authorship of Hercules on Oeta has also been questioned. Seneca's tragedies Fabulae crepidatae (tragedies with Greek subjects): Hercules or Hercules furens (The Madness of Hercules) Troades (The Trojan Women) Phoenissae (The Phoenician Women) Medea Phaedra Oedipus Agamemnon Thyestes Hercules Oetaeus (Hercules on Oeta): generally considered not written by Seneca. First rejected by Daniël Heinsius. Fabula praetexta (tragedy in Roman setting): Octavia: almost certainly not written