The traditional Western day for the Christmas festival, 25th December, goes back as far as Hippolytus, loc. cit.; the traditional Eastern day, 6th January, as far as the Basilidian Gnostics (but in their case only as a celebration of the Baptism), mentioned by Clement of Alexandria, loc. cit.
- The earliest known calculations, by Basilidian Gnostics, quoted in Clem.
Characteristically, in these Basilidian systems the figure of the " Mother " or of Sophia does not appear.
This peculiarity the Basilidian system shares with that of Satornil of Antioch, which has only come down to us in a very fragmentary state, and in other respects recalls in many ways the popular Gnosticism.