单选题 .  ①The manuscripts of the eight extant Latin tragedies identify the plays as the Marci Lucii Annei Senecae Tragoediae. ②Since nobody of that name is known, modern scholars believe the dramas to be the work of Lucius Annaeus Seneca the Younger, the well-known philosopher, orator and politician. ③Clearly the tragedies were written during Seneca's lifetime: internal references to earlier poets, most notably Ovid, indicate that the dramas cannot have been composed prior to the second decade C.E., and the plays must have been written by 96C.E., when Quintilian quotes Medea, one of the tragedies.
    ①It is remarkably, however, that Seneca himself never mentions the plays, since there are certain passages in them that could be used to illustrate points of his philosophy. ②There are at least two possible explanations. ③In the early Roman Empire, playwrights were sometimes exiled or executed for line constructed as directed against the emperor; thus, Seneca's silence may be simple prudence. ④But if anyone could safely attach his name to dramas, surely it would be Seneca, the emperor's tutor. ⑤And although Herrmann offers Seneca's modesty as an explanation, Seneca is not averse to referring to his other writings. ⑥The evidence for equating Seneca with the author of the tragedies seems circumstantial.8.  The author mentions Medea primarily in order to ______