The "Twelve Days of Christmas" was originally written to help Catholic children in England, remember different aspects of their faith, during the times of persecution by the monarchs.
The "true love" represented God, and the gifts all represented different ideas:
The "Partridge in a pear tree" was Christ.
2 Turtle Doves = The Old and New Testaments
3 French Hens = Faith, Hope and Charity– the Theological Virtues
4 Calling Birds = the Four Gospels and/or the Four Evangelists
5 Golden Rings = The first Five Books of the Old Testament, the "Pentateuch", which relays the history of man’s fall from grace.
6 Geese A-laying = the six days of Creation
7 Swans A-swimming = the seven gifts of the Holy Spirit, the seven sacraments
8 Maids A-milking = the eight beatitudes
9 Ladies Dancing = the nine Fruits of the Holy Spirit
10 Lords A-leaping = the ten commandments
11 Pipers Piping = the eleven faithful apostles
12 Drummers Drumming = the twelve points of doctrine in the Apostle’s Creed