As to who this Hippolytus was, Eusebius and subsequent students among the Fathers appear to have known scarcely anything. Eusebius speaks of the many writings of Hippolytus, and gives the titles of some of them, and describes one more particularly. This was a treatise Concerning the Pascha, in which was to be found a certain sixteen-year rule (canon) about the Pascha, the boundary of the writer’s computation being the first year of the Emperor Alexander[151], i.e. Alexander Severus, whose first year was A.D. 222.
The brief statement of Eusebius, dull and prosaic in itself, acquired suddenly a new and extraordinary interest in the year 1551, when during some excavations made in the neighbourhood of Rome, in the Via Tiburtina (the road to Tivoli), a much shattered statue was unearthed, which on being pieced together exhibited, on the sides of the chair in which the figure of a venerable looking man was represented as seated, two elaborate numerical tables, in Greek characters, one showing the day of the month on which the Pascha, or fourteenth day of the moon, would fall from A.D. 222 to A.D. 333: the other showing, for the same number of years, the day of the month upon which Easter ought to be kept. The statue, as restored, may now be seen in the Museum of the Vatican. The Tables are constructed in seven columns of sixteen years each. On the back of the chair were inscribed in Greek the titles of various books, many of which corresponded with the titles of works attributed to Hippolytus by Eusebius. There could be no reasonable doubt that the statue was the statue of Hippolytus, and that the Tables represented his calculations as to the time for keeping Easter.
A further confirmation of the correctness of this inference (though confirmation was indeed scarcely needed) emerged when a Syriac version of the Cycle of Hippolytus was discovered in a chronological treatise by Elias of Nisibis[152]. It corresponds exactly with the Tables inscribed on the chair.
An examination of the Tables of Hippolytus reveals that he assumed ‘that after eight years the full moons returned to the same day of the solar month; and he took notice that after sixteen years the days of the week moved one backward; that is to say, the full moon in the first year of the cycle being Saturday, April 13, after sixteen years it would be Friday, April 13, and so on[153].’ But for the purposes of what he supposed would be a perpetual Kalendar, Hippolytus desired to ascertain after what interval the full moon would fall not only on the same day of the solar month, but on the same day of the week. He assumed that this would happen after seven cycles of sixteen years.
We can also infer that Hippolytus probably placed the vernal equinox on March 18, for every full moon entered in his Tables is placed either on (as in the case of A.D. 235) or after that date.
Again, the examination of his Tables reveals what may seem to us the somewhat arbitrary regulation that if the full moon fell upon Saturday the Feast of the Resurrection should not be kept on the following day, but on Sunday a week later. The explanation probably is that it was considered that Easter should never be held earlier than the sixteenth day of the moon, that is, two days after the day of the Crucifixion. If the full moon fell upon Friday, then the following Sunday would be Easter; but if the full moon fell upon Saturday, the day of the Crucifixion was taken to be the following Friday, and Easter would be two days after.
No Easter cycle yet devised is free from errors, which have to be met by adjustments; but the Cycle of Hippolytus was such that the errors accumulated rapidly. It was more than two days wrong at the end of the first sixteen years; and five days wrong at the end of the second cycle; at the end of the third cycle it would be nine days wrong[154]. This must have been soon discovered; and the cycle had to be discarded. It is the earliest Easter cycle known to us.
A cycle on the same lines as that of Hippolytus, which has been (probably incorrectly) attributed to St Cyprian, will be found in Fell’s edition of Cyprian (1682), among the works commonly assigned to that writer. By whomsoever it was composed it is ushered in with a great flourish of trumpets, and the author feels sure that he has been led by nothing short of divine inspiration to the discovery. These Tables can be assigned to A.D. 243. One cannot but suspect that the author had got hold of the Hippolytean Tables before their worthlessness was discovered.
Such seem to have been the best efforts of the learning of Western Christendom in the third century to deal with the Paschal problem. Nor at this period was the Church of Alexandria, which at a later date became the paramount authority on such questions, any better equipped. Dionysius, about the middle of the third century, justly styled by Eusebius ‘the great bishop of Alexandria,’ made use of the eight-year cycle, which, like its variant, the sixteen-year cycle, gathered error rapidly.
It was, however, another distinguished Alexandrian, more than a quarter of a century later, who was the first, so far as we know, to make use of the old nineteen-year cycle for the determination of Easter. This was Anatolius, a native of Alexandria, and eminent for learning of various kinds (among which arithmetic, geometry, and astronomy are particularised), who became bishop of Laodicea in Syria Prima in A.D. 270. The nineteen-year cycle, with some modifications, eventually, though slowly, displaced all rivals[155].