5 Now, if this be not the case, all hope of help is taken away, and it will be doubtful whether you are heard by the gods or not, if ever you perform the sacred rites with due ceremonies. For, to make it clear, let us suppose that there is a temple of some deity in the Canary Islands, another of the same deity in remotest Thyle, also among the Seres, among the tawny Garamantes, and any others who are debarred from knowing each other by seas, mountains, forests, and the four quarters of the world.
If they all at one time beg of the deity with sacrifices what their wants compel each one to think about, what hope, pray, will there be to all of obtaining the benefit, if the god does not hear the cry sent up to him everywhere, and if there shall be any distance to which the words of the suppliant for help cannot penetrate? For either he will be nowhere present, if he may at times not be anywhere, or he will be at one place only, since he cannot give his attention generally, and without making any distinction. And thus it is brought about, that either the god helps none at all, if being busy with something he has been unable to hasten to give ear to their cries, or one only goes away with his prayers heard, while the rest have effected nothing.
Source: Against the Heathen (New Advent)