There seems a sort of general agreement among modern historians of Greece to accept the 1st Olympiad (776 B.C.) as the trustworthy starting point of solid Greek chronology. Even Grote, so sceptical about legends, and so slow to gather inferences from them, accepts this datum. There is only one exception, I think, to be found in Sir George Cox, who evidently rejects the Olympiad register, who will not set down in his chronology any figure higher than 670 B.C., and even that under the protest of a query.
When we come to inquire on what authority so early a date can be securely established, we find a sort of assumption, not supported by argument, that from 776 onward the Eleians kept a regular record of their great festival, and as a matter of fact such a record is extant. It was generally acknowledged and cited by the later historians of Greece, who determined events according to it. Above all, the critical doubts of philologists are soothed by the supposed authority of Aristotle, who is reported to have made researches on the question, and to refer to the list as if authentic; he even mentioned a discus at Olympia with Lycurgus' name inscribed upon it, but in what work, and for what purpose, is unknown. I know that Aristotle is considered an infallible authority by modern philologists, so much so that those who are ready enough to deny even general inspiration to other authorities, seem almost to attribute verbal inspiration to this philosopher. One other Greek authority shares with him this pre-eminence—the historian Thucydides. And it so happens that in his Sicilian Archaeology (book vi.) Thucydides gives a number of dates, with precision and without hesitation, which reach back to 735 B.C., and therefore persuades his commentators that accurate dates were attainable up to a period close to the 1st Olympiad. These are apparently the silent reasons which have determined the general consent of modern historians.