The next point to be considered is the number of the entrances which had to be provided when the scenery was erected, and the stage was made ready for a dramatic performance. Pollux and Vitruvius, in speaking of the scenery and stage decorations, agree in saying that there were three doors at the back of the stage.[592] But this statement is much too universal. In the majority of cases, no doubt, there were three such doors. When the scene represented a palace, or temple, or dwelling-house, three doors appear to have been always used. But when the scene was of an exceptional character, the number of the entrances from the back of the stage would vary according to the requirements of the play. For instance, in the Philoctetes there would only be a single entrance, that from the cavern. In the first part of the Ajax the only entrance would be that leading out of the tent; in the second part there would be no entrance at all, the background consisting merely of a solitary region by the sea-shore. In the Cyclops, the only opening at the back of the stage was the mouth of Polyphemus’ cave. In such plays as the Prometheus of Aeschylus, and the Andromeda of Euripides, the background consisted of rocks and cliffs, and there was no entrance from that quarter. It is clear, therefore, that the statement that a Greek scene was provided with three doors or entrances at the back is not universally true, but only applies to the majority of cases. Some details concerning the character of the three doors may be gathered from the statements in Pollux and Vitruvius.[593] When the scene was a palace, the central door was decorated with regal grandeur. The side-doors were supposed to lead to the guest-chambers. Occasionally one of the side-doors led to a guest-chamber, the other to a slaves’ prison. In comedy, the character and arrangement of the doors would vary considerably, according as the scene was laid in front of one, or two, or three dwelling-houses. In the last case, of which an example is supplied by the Acharnians, there would be one door for each of the three houses. Sometimes one of the side-doors represented the way into an outhouse, or workshop, or stable. Sometimes it led into a temple, as in the Thesmophoriazusae. In comedy, no doubt, there was much greater diversity as to scenic details than in tragedy.