Cutting the thread represents the encounter between God as a child and the wise men, known as the epiphany.
Every January 6th, several families are accustomed to give gifts, this as a representation of the gifts that the wise men took to the baby Jesus. Although this custom is more practiced in the center of the country, like Mexico City.
The oval shape of the thread represents the infinite circle of love for God, without beginning or end. It also evokes the crowns of the Wise Men.
In Mexico the Wise Men were known by the Catholic missionaries who spread it from the sixteenth century and at the same time introduced the habit of giving gifts to children.
The custom of cutting the thread was originated in the Middle Age in France. To Christianize the tradition, it was introduced a bean, which symbolized the flight of Joseph and Mary to hide the child Jesus and save him from the persecution of King Herod. The candies or crystallized fruits serve as the distractions of the world that prevent us from finding Jesus.
At the moment that bean has been replaced by a little plastic doll (several of them) that is introduced in the bread, in Mexico if your slice has a doll this has no other meaning than to host a party on February 2 with a lot of tamales, the Candelaria Day.