Nor is it necessary to suppose that all these priests and priestesses were impostors. Having been trained up from infancy to believe that the inspirations were real, they would continue to look upon them as such all their lives. Even at the present day we shall all, if we closely scrutinize our mental habits, find ourselves continuing to take for granted, in our maturer years, what we inconsiderately imbibed or were erroneously taught in infancy, and that, often, in cases where the most obvious dictates of reason, or even the plain testimony of our senses, might show us that our notions are false. The priests and priestesses, therefore, who imposed on the rest of mankind, may have been as honestly and as deep in the delusion themselves as any of their dupes.
The answers of the oracles were generally vague and indefinite, and susceptible of almost any interpretation, according to the result. Whenever the event corresponded with the prediction, or could be made to correspond with it by the ingenuity of the commentators, the story of the coincidence would, of course, be every where spread abroad, becoming more striking and more exact at each repetition. Where there was a failure, it would not be direct and absolute, on account of the vagueness and indefiniteness of the response, and there would therefore be no interest felt in hearing or in circulating the story. The cases, thus, which would tend to establish the truth of the oracle, would be universally known and remembered, while those of a contrary bearing would be speedily forgotten.
There is no doubt, however, that in many cases the responses were given in collusion with the one who consulted the oracle, for the purpose of deceiving others. For example, let us suppose that Croesus wished to establish strongly the credibility of the Delphic oracle in the minds of his countrymen, in order to encourage them to enlist in his armies, and to engage in the enterprise which he was contemplating against Cyrus with resolution and confidence; it would have been easy for him to have let the priestess at Delphi know what he was doing on the day when he sent to inquire, and thus himself to have directed her answer. Then, when his messengers returned, he would appeal to the answer as proof of the reality of the inspiration which seemed to furnish it. Alexander the Great certainly did, in this way, act in collusion with the priests at the temple of Jupiter Ammon.