The 20th century French Jesuit Jean Daniélou on this season:
We live always during Advent. We are always waiting for the messiah to come. The messiah has come, but is not yet fully manifest. The messiah is not fully manifest in each of our souls, not fully manifest in humankind as a whole: that is to say, that just as Christ was born according to the flesh in Bethlehem of Judah, so must he be born according to the spirit in each of our souls. (from Advent, 1950, later translated and published by Sheed and Ward in 1962.)