The core of the esoteric theology of the Maori was the concept of the Supreme Io which remained wholly unrevealed to foreign inquirers for many decades after the first contact of Europeans and Maori. I cannot help feeling that our lack of knowledge of such a supreme god in other island groups is due largely to the fact that the knowledge was limited to the ancient priesthood, whose rules would have compelled them to conceal from outsiders the most sacred of the lore; while personal instinct would have at the same time have led them to shelter their hallowed beliefs from strangers with the attitude typical of practically all the early inquirers. With the ancient priest hoods, the knowledge of the great body of the most sacred Polynesian lore died. The following pictures well the attitude of Maori priests towards the indiscreetly inquisitive and disrespectful. Tregear writes:
'C.O. Davis mentions that when attempting to question an old priest on the subject of the ancient Maori worship of the Supreme Being he was refused information, and politely referred to another priest 100 miles away. Probably that priest would have referred him again to someone else and so on. Each initiate into the sacred mysteries considered his knowledge as a trust to be guarded against the outer world, and it is only under most exceptional circumstances that information could be acquired. Some gods could only be named in the Whare Kura and Wharewanagna (temples) of the tribe. To utter "the ineffable name" (Io) under a roof of any kind was to blaspheme most frightfully, and would be a sacrilege that only an ignorant person (religiously ignorant) like a European would have the depravity to attempt. Even the names of ancestors, as god-descended, would not be regarded as treated with due respect if mentioned at certain times or in unsuitable localities. A European student of Maori lore once ventured to speak to an old priest whom he met in a country store (shop) and asked him some question about ancient history. The Maori turned round with a disgusted look and remarked, "This is no place in which to speak of solemn things,". . . . . Only one who loved the enquirer and dared unknown terrors for the sake of that love would answer such questions (about sacred things) or repeat the consecrated hymns for him. It is not unusual for a priest after going a certain length to say, "If I tell you any more death will overtake me," or "I must not repeat what follows, because there is now no priest alive sacred enough to perform the ceremonies necessary to purify me from such sacrilege." Another has been known to say, "The presence of the Christian God has silenced the Maori gods, but the gods of the Maori still hold us in their power, and if I break their laws they will punish me with death."'
The mere fact of the existence of Io was unknown to most Maoris. Best writes that:
'The number of men initiated into the cult of Io was but small; only members of the higher grade
of priestly experts and men of high-class families, were allowed to learn the ritual pertaining to
it. The common folk apparently had no part in it and it is doubtful if they were even allowed to
know the name of the Supreme Being. The cult of Io was an esoteric one; that of the lower
tribal gods may be termed exoteric. All ritual and ceremonial pertaining to Io was retaining in
the hands of the superior priesthood, by no means a numerous body. It may be described as an
aristocratic cultus, known only to such experts and the more important chiefs. It is quite
probable, indeed, that this superior creed may have been too exalted for ordinary minds, that
such would prefer to depend on more accessible and less moral deities.
'It is interesting to note that no form of offering or sacrifice was made to Io, that no image of him was ever made, and that he had no aria, or form of incarnation, such as inferior gods had.'