It remains to consider briefly certain moral aspects of his cult. The morality attaching to the oath, so deeply rooted in the con science of primitive peoples, was expressed in the cult of Zeus Horkios, the god who punished perjury (Pausan. v. 24. 9). The whole history of Greek legal and moral conceptions attaching to the guilt of homicide can be studied in relation to the cult-appel latives of Zeus. The Greek consciousness of the sin of murder, only dimly awakened in the Homeric period, and only sensitive at first when a kinsman or a suppliant was slain, gradually expands till the sanctity of all human life becomes recognized by the higher morality of the people ; and the names of Zeus Meilichios, the dread deity of the ghost-world whom the sinner must make "placable," of Zeus Hikesios and Prostropaios, to whom the conscience-stricken outcast may turn for mercy and pardon, play a guiding-part in this momentous evolution.
But it was in the poets and philosophers that this evolution attained its end. Most of them were believers in a supreme power, present always and everywhere, and some of them—Empedocles, Aeschylus, Plato—gave to this supreme power the name of Zeus.
"Zeus, whosoever he is,—if this name be pleasing unto him, by this name do I call him,—weighing all things in the balance, nought can I conjecture save only Zeus." (Aeschylus, Agamemnon, 16o et seq.; cf. f rag. 7o, Naucks 2nd ed.). He is the spirit of the world, the law of the universe, the universal reason, and all other gods are only parts or manifestations of him (cf. Diog. Laert. vii. 147). Moreover, as we may see from the "hymn" of Cleanthes (f rag. 48), and from St. Paul's quotation from it or Aratus (Acts xvii., 28—Arat., phaen. 5), he was conceived by the Stoics as the father of the human race, who "alone of mortal things that live and move upon the earth" were created in his image.