As regards the use of these side-entrances the Athenians had a special regulation which was due entirely to local causes. The theatre at Athens was situated in such a position that the western side looked towards the city and the harbour, the eastern side towards the open country. In consequence of this fact the side-entrances upon the Athenian stage came to acquire a peculiar significance. If a man entered by the western side, it was understood that he was coming from the city where the scene of the action was laid, or from the immediate neighbourhood; or else that he had arrived from distant parts by sea, and was coming from the harbour. The eastern entrance was reserved for people who had journeyed from a distance by land. The same regulation was applied to the entrances to the orchestra. If a chorus came from the city, or the harbour, or the suburbs, it used the western parodos; if it came by land from a distance, it used the eastern.[605] It is obvious that at Athens, where play-bills were unknown, a conventional arrangement of this kind would be of great assistance to the audience, and would enable them to follow the action of the piece with greater ease and intelligence than they could otherwise have done. The custom originated in the topographical situation of the Athenian theatre, but was afterwards adopted in all other Greek theatres, and became a conventional rule of the Greek stage. The entrances to the right of the audience were used by persons from the neighbourhood; the entrances to the left by persons from a distance. § 4. _Changes of Scene._