Today was Yom Kippur, and it was the holiest day in Judaism. Therefore it was also a special Punishment Day for a penitatas, like Diana.
However, during Yom Kippur, like during Sabbath, physical labor was not permitted. So, while little Di was supposed to receive lots of special punishment day spankings today, they were not to come from neither her mommy nor her daddy. Lucas and Ruth were ready to leave for the Synagogue, but they were waiting for someone first.
They had asked a Shabbos goy to take care of Diana's punishment today. A person that is non Jewish, and assists Jewish individuals by performing the acts that are forbidden by Jewish law on Sabbath. Or in this case Yom Kippur.
Usually, when the parents of a penitatas went out for the night for a party or another type of social gathering, they hired a babysitter from the neighborhood, usually a Completas or a Voluntaras. Or they were left at the house of other couple that also had a license to take care of penny kids. (And some