Beit-Hallahmi uses a curve attributed to Furlong showing that holidays in all religions tend to duster around the astronomical events of the vernal and autumnal equinoxes, or of the winter and summer solstices. The major holidays tend to group around the vernal and autumnal equinoxes. Beit-Hallahmi traces the history of the celebration of the sun through holidays that clustered around the winter solstice. Both Hannukah and Christmas are relatively recent arrivals in this group; both have lights as important parts of the ritual. Both are also seen as part of the attempt, as people, societies, and their religions changed, to move from human sacrifice to animal sacrifice to symbolic sacrifice, as represented by the burning candle.