The eight maids a-milking represent the Eight Beatitudes found in the Gospel of Matthew.
Matthew Chapter 5:
“And seeing the multitudes, he went up into a mountain, and when he was set down, his disciples came unto him. And opening his mouth, he taught them, saying:
1) Blessed are the poor in spirit: for theirs is the kingdom of heaven.
2) Blessed are the meek: for they shall possess the land.
3) Blessed are they that mourn: for they shall be comforted.
4) Blessed are they that hunger and thirst after justice: for they shall have their fill.
5) Blessed are the merciful: for they shall obtain mercy.
6) Blessed are the clean of heart: for they shall see God.
7) Blessed are the peacemakers: for they shall be called children of God.
8) Blessed are they that suffer persecution for justice' sake: for theirs is the kingdom of heaven.
Blessed are ye when they shall revile you, and persecute you, and speak all that is evil against you, untruly, for my sake: Be glad and rejoice, for your reward is very great in heaven. For so they persecuted the prophets that were before you.” “Dear Jesus, teach me to understand all Thy words, and to behave the way a true Christian should. Amen.
See also - praying the beatitudes
Praying through the beatitudes
Understanding the beatitudes