This fable would intimate a Hellenic origin, since Deucalion is the fabled founder of the Hellenes; but out of twelve tribes which composed the confederacy, only three were Hellenic, and the rest Pelasgic. But with the increasing influence of the Dorian oracle of Delphi, with which it was connected, it became gradually considered a Hellenic institution. It is not possible to decipher the first intention of this league. The meeting was held at two places, near Anthela, in the pass of Thermopylae, and Delphi; at the latter place in the spring, at the former in the autumn. If tradition imputed to Amphictyon the origin of the council, it ascribed to Acrisius, king of Argos , the formation of its proper power and laws. He is said to have founded one of the assemblies, either that in Delphi or Thermopylae (accounts vary), and to have combined the two, increased the number of the members, and extended the privileges of the body. We can only interpret this legend by the probable supposition, that the date of holding the same assembly at two different places, at different seasons of the year, marks the epoch of some important conjunction of various tribes, and, it may be, of deities hitherto distinct. It might be an attempt to associate the Hellenes with the Pelasgi, in the early and unsettled power of the former race: and this supposition is rendered the more plausible by the evident union of the worship of the Dorian Apollo at Delphi with that of the Pelasgian Ceres at Thermopylae . The constitution of the league was this - each city belonging to an Amphictyonic state sent usually two deputies - the one called Pylagoras, the other Hieromnemon. The functions of the two deputies seem to have differed, and those of the latter to have related more particularly to whatsoever appertained to religion. On extraordinary occasions more than one pylagoras was deputed - Athens at one time sent no less than three. But the number of deputies sent did not alter the number of votes in the council. Each city had two votes and no more, no matter how many delegates it employed.
All the deputies assembled, - solemn sacrifices were offered at Delphi to Apollo, Diana, Latona, and Minerva; at Thermopylae to Ceres. An oath was then administered, the form of which is preserved to us by Aeschines.
"I swear," runs the oath, "never to subvert any Amphictyonic city - never to stop the courses of its waters in peace or in war. Those who attempt such outrages I will oppose by arms; and the cities that so offend I will destroy. If any ravages be committed in the territory of the god, if any connive at such a crime, if any conceive a design hostile to the temple, against them will I use my hands, my feet, my whole power and strength, so that the offenders may be brought to punishment."
Fearful and solemn imprecations on any violation of this engagement followed the oath.
These ceremonies performed, one of the hieromnemons  presided over the council; to him were intrusted the collecting the votes, the reporting the resolutions, and the power of summoning the general assembly, which was a convention separate from the council, held only on extraordinary occasions, and composed of residents and strangers, whom the solemnity of the meeting congregated in the neighbourhood.
VI. Throughout the historical times we can trace in this league no attempt to combine against the aggression of foreign states, except for the purposes of preserving the sanctity of the temple. The functions of the league were limited to the Amphictyonic tribes and whether or not its early, and undefined, and obscure purpose, was to check wars among the confederate tribes, it could not attain even that object. Its offices were almost wholly confined to religion. The league never interfered when one Amphictyonic state exercised the worst severities against the other, curbing neither the ambition of the Athenian fleet nor the cruelties of the Spartan sword. But, upon all matters relative to religion, especially to the worship of Apollo, the assembly maintained an authority in theory supreme - in practice, equivocal and capricious.
As a political institution, the league contained one vice which could not fail to destroy its power. Each city in the twelve Amphictyonic tribes, the most unimportant as the most powerful, had the same number of votes. This rendered it against the interest of the greater states (on whom its consideration necessarily depended) to cement or increase its political influence and thus it was quietly left to its natural tendency to sacred purposes. Like all institutions which bestow upon man the proper prerogative of God, and affect authority over religious and not civil opinions, the Amphictyonic council was not very efficient in good: even in its punishment of sacrilege, it was only dignified and powerful whenever the interests of the Delphic temple were at stake. Its most celebrated interference was with the town of Crissa, against which the Amphictyons decreed war B. C. 505; the territory of Crissa was then dedicated to the god of the temple.