Augustine notices that the Greek word for a fish, which, containing the initial letters of the name and titles of Christ, had been adopted by the Early Church as its sacred symbol, contains also the initial letters of some prophetic lines ascribed to the Sibyl of Erythra.(706) The Pagans, it is true, accused their opponents of having forged or interpolated these prophecies;(707) but there was not a single Christian writer of the patristic period who disputed their authority, and there were very few even of the most illustrious who did not appeal to them. Unanimously admitted by the Church of the Fathers, they were unanimously admitted during the middle ages, and an allusion to them passed into the most beautiful lyric of the Missal. It was only at the period of the Reformation that the great but unhappy Castellio pointed out many passages in them which could not possibly be genuine. He was followed, in the first years of the seventeenth century, by a Jesuit named Possevin, who observed that the Sibyls were known to have lived at a later period than Moses, and that many passages in the Sibylline books purported to have been written before Moses. Those passages, therefore, he said, were interpolated; and he added, with a characteristic sagacity, that they had doubtless been inserted by Satan, for the purpose of throwing suspicion upon the books.(708) It was in 1649 that a French Protestant minister, named Blondel, ventured for the first time in the Christian Church to denounce these writings as deliberate and clumsy forgeries, and after much angry controversy his sentiment has acquired an almost undisputed ascendancy in criticism.