On the evening of the Winter Solstice we carry out our sacred rites to the Mothers, the divine Matronae of our folk. This ancient festival which is part of Yule is referred to by Bede in his De temporum ratione 13 that the heathen Angles carried out a sacrifice in the "modraniht id est matrum noctrum", meaning "the Modraniht, that is, in the night of mothers." Rudolf Simek in his Dictionary of Northern Mythology comments:
"Thus it corresponds to other Germanic Yule-tide festivals; the idea that it might have been a Celtic festival is largely refuted nowadays. The Modraniht as a Germanic sacrificial festival should be associated with the > Matron cult of the West Germanic peoples on the one hand, and to the disablot and > Disting known from medieval Scandinavia on the other hand and is chronologically to be seen as a connecting link between these Germanic forms of cult."
According to Gale R. Owen Modraniht was actually held on 25th of December:
"The winter festival which Bede called Mothers' Night marked the pagan New Year and was held on 25 December. It is likely that this Yule festival (the pagan name for December and January, we may remember, was giuli) involved the bringing in of evergreens, the burning of a Yule log and a feast centred round a boar's head, since these non-Christian features became associated with the Christmas festival celebrated at that time." (Rites and Religions of the Anglo-Saxons, 1981)
"began the year on the 8th kalends of January [25 December], when we celebrate the birth of the Lord. That very night, which we hold so sacred, they used to call by the heathen word Modranecht, that is, "mother's night", because (we suspect) of the ceremonies they enacted all that night." (Bede)
Tony Linsell in his excellent book Anglo-Saxon Mythology, Migration & Magic (1984) speculates:
"That the heathen English used the month as a measure of time is evident from Bede's De Temporum Ratione, written in 725, in which we also learn that the new year began on Midwinter Day (25th December, that is the night of 24th/25th December). On the following night, Mothers' Night, certain ceremonies took place but we do not know what they were, although it seems reasonable to suppose that it was a time to give praise to the Earth Mother, Nerthus (or Frig), and to her son Ing, the God of Brightness."
Kathleen Herbert makes the following very interesting and important point:
"The most sacred night, when the new Year began, was called Modranect, Mothers' Night. 'Modra' is plural; it was the night 'of the Mothers' not 'of the Mother'. He says that it was so called from the ceremonies which took place then; he does not describe them, nor does he say who the Mothers were." (Looking for the Lost Gods of England, 1994)
Mr Linsell refers in his book to a theory of Kathleen Herbert's that "the celebration may have been for the birth, to Frig (Nerthus), of Ing, the God of Brightness, with whom the turning of the year is associated. The symbol of Ing is the boar, and a boar's head is traditionally served on a bed of greenery on Midwinter Day, which is also Christmas Day."
In the Eddas the God Frey was associated with the sun and portrayed as a God of brightness so it is appropriate when we consider that we are at the point of the year when the sun is beginning its long journey of return that the sun or Ing is being given birth to by His mother, who we speculate to be Nerthus.