The size of ancient theaters exercised an influence also in another direction. In the absence of arches and domes or modern steel girders it was impossible to roof over such a structure without a multitude of supports to obstruct the view and hearing. Accordingly, the proceedings were exposed to every caprice of the weather. For example, in the time of Demetrius Poliorcetes an unseasonable cold spell and frost broke up the procession. On the other hand the lack of an adequate and easily controlled artificial illuminant such as gas or electricity would have prevented the satisfactory lighting of a roofed theater, could they have built one. Therefore, like the Elizabethans, their dramas were presented in the daytime, and the constant harmony between lighting effects and dramatic situation, which to us is a commonplace, was entirely beyond their powers. But since it was also beyond their ken, it doubtless did not bother them especially, and like much else was safely left to the well-trained imaginations of the spectators. Thus dramatic characters frequently address the heavenly constellations in broad daylight, and ostensibly the entire action of the _Rhesus_ and much of that in Euripides’ _Cyclops_ fall within the hours of night. Nevertheless, we know that the playwrights were sometimes self-conscious concerning this discrepancy. In Aristophanes’ _Frogs_ most of the action is supposed to be laid in Hades, and ancient opinion was unanimous in considering that a place of gloom. Since the poet could not count upon the sun going behind a cloud to suit his convenience, he undertook to put the audience on their guard against the incongruity. Toward the beginning of the play, when Dionysus is seeking directions for his journey to the lower world and the scene is still upon earth, Heracles tells him: “Next a breathing sound of flutes will compass you about and you will see a light most fair, _even as here_” (vss. 154 f.). Furthermore, shortly after the action is transferred to the realm of Pluto, the matter is once more called to the spectators’ attention by the chorus of initiates singing (vss. 454 f.): “We alone have a sun and gracious light.”