This, the second source of religion, though more subtle and refined in its creations, had still its origin in the same human causes as the first, viz., anticipation of good and apprehension of evil. Of deities so created, many, however, were the inventions of poets-- (poetic metaphor is a fruitful mother of mythological fable)--many also were the graceful refinements of a subsequent age. But some (and nearly all those I have enumerated) may be traced to the earliest period to which such researches can ascend. It is obvious that the eldest would be connected with the passions--the more modern with the intellect.
It seems to me apparent that almost simultaneously with deities of these two classes would arise the greater and more influential class of personal divinities which gradually expanded into the heroic dynasty of Olympus. The associations which one tribe, or one generation, united with the heaven, the earth, or the sun, another might obviously connect, or confuse, with a spirit or genius inhabiting or influencing the element or physical object which excited their anxiety or awe: And, this creation effected--so what one tribe or generation might ascribe to the single personification of a passion, a faculty, or a moral and social principle, another would just as naturally refer to a personal and more complex deity:--that which in one instance would form the very nature of a superior being, in the other would form only an attribute--swell the power and amplify the character of a Jupiter, a Mars, a Venus, or a Pan. It is in the nature of man, that personal divinities once created and adored, should present more vivid and forcible images to his fancy than abstract personifications of physical objects and moral impressions. Thus, deities of this class would gradually rise into pre-eminence and popularity above those more vague and incorporeal--and (though I guard myself from absolutely solving in this manner the enigma of ancient theogonies) the family of Jupiter could scarcely fail to possess themselves of the shadowy thrones of the ancestral Earth and the primeval Heaven.
A third source of the Grecian, as of all mythologies, was in the worship of men who had actually existed, or been supposed to exist. For in this respect errors might creep into the calendar of heroes, as they did into the calendar of saints (the hero-worship of the moderns), which has canonized many names to which it is impossible to find the owners. This was probably the latest, but perhaps in after-times the most influential and popular addition to the aboriginal faith. The worship of dead men once established, it was natural to a people so habituated to incorporate and familiarize religious impressions--to imagine that even their primary gods, first formed from natural impressions (and, still more, those deities they had borrowed from stranger creeds)--should have walked the earth. And thus among the multitude in the philosophical ages, even the loftiest of the Olympian dwellers were vaguely supposed to have known humanity;--their immortality but the apotheosis of the benefactor or the hero.