Glossa Ordinaria

And I will bewail, etc. And he did to her, etc. A chaste virgin, that is, the Church, etc., up to on account of which also two testaments are spoken of. From that time the custom grew. But as to what was done by ordinance in Israel, that from days to days they came together to lament the daughter of Jephte, four days in the year, I do not think it signifies anything after the holocaust is fulfilled, which will be in eternal life, but the past times of the Church, in which were the blessed that mourn. By the four days her universality was figured, on account of the four parts of the world through which she is spread far and wide. But as to the proper sense of the history, I do not think the Israelites decreed this except because they understood that in her the judgement of God had been shown rather for the striking of the father, lest anyone thereafter should vow such a sacrifice. For why was a lamentation decreed, if that vow is a matter of gladness?