Light from The Cross,
upon Thy Christmas shine.

Nexus mysteriorum, is a Latin phrase expressing the belief that all the Mysteries are inter-related. This image shows the influence of this Church teaching developed in the first Vatican Council (1869-1870).
It is unclear whether this card was published in celebration of Easter or Christmas, because, clearly it was meant to show that the feasts are inseparable: it is the Cross of Christ that illumines the beauty of Christmas.