The Latin play is introduced by a prologue which is spoken by the God Mercury, and was explanatory to the audience of the circumstances preceding the opening of the piece, and the situation of the principal characters. The term _prologue_ has been very arbitrarily used. In one sense it merely signified the induction to the dramatic action, which informed the spectator of what was necessary to be known for duly understanding it. Aristotle calls that part of a tragedy the prologue, which precedes the first song of the chorus.(229) In the Greek tragedies, the prologue was often a long introductory and narrative monologue. Sophocles, however, so _dialogued_ this part of the drama, that it has no appearance of a contrivance to instruct, but seems a natural conversation of the _dramatis personæ_. Euripides, on the other hand, fell more into the style of the formal narrative prologue, since, before entering on the action or dialogue, one of the persons destined to bear a part in the drama frequently explained to the audience, in a continued discourse, what things seemed essential for understanding the piece. Sometimes, however, in the Greek tragedies, the speaker of this species of prologue is not a person of the drama. In general, these artificial prologues of explanatory narration are addressed directly to the spectators, and hence approach nearly to the prologue, in our acceptation of the term. The poets of the ancient comedy, as we see from Aristophanes, usually adopted, like Sophocles, the mode of explaining preliminary circumstances in the course of the action, whence it has been considered that the old Greek comedies have no prologue; and they certainly have none in the strict modern sense, though the method of Euripides has been employed to a certain degree in the _Wasps_ and _Birds_, in the former of which Xanthias, interrupting the dialogue with Sosias, turns abruptly to the spectators, and unfolds the argument of the fable. The poets of the middle and new comedy, while departing from Aristophanes in many things, followed him in the form of the prologue; and, as they improved in refinement, interwove still closer the requisite exposition of the fable with its action. The Romans thus found among the Greeks, prologues in a continued narrative, and prologues where the exposition was mixed with the action. From these models they formed a new species, peculiar to themselves, which is entirely separated from the action of the drama, and which generally contains an explanation of circumstances and characters, with such gentle recommendation of the piece as suited the purpose of the author. We shall find that the Latin prologues, dressed up in the form of narrative, sometimes preceded the dramatic induction of the action, and at other times, as in the _Miles Gloriosus_, followed it. The prologue of the _Mostellaria_ is on the plan adopted by Aristophanes, and that of the _Cistellaria_ is conformable to the practice of our own theatre.