Challenged, as a bit of a wind-up, to paint a Christmas scene "with snow and sleighbells, elves, mistletoe and all the trimmings," the artist essayed the work below.

The title given it was 'Baubles'. The fragile glass globes and Holzschnitt wooden angels are quite intentionally a riposte to the challenge, and insist that they have their place between Heaven and Earth. The star of Bethlehem, the herald angels, the mud-baked Nubian domes on the hillside: what could be out of place?

Benedict XVI, Joseph Ratzinger, possesses apart from anything else an engaging literary style, diffidently suggesting to  the reader the unwitting fallacies underlying positions of doubt. It is the prologue to his study of Christ which, published in 2012 after volumes I and II of the main study, seeks to interpret what Mark and Luke relate in the prologues to their gospels: the story of the nativity and childhood of Christ.

Sure, Matthew says the whole thing came to pass in fulfilment of a prophecy of Isaiah (7,14) from 733BC. King Ahaz of Judah pursues realpolitik and makes an alliance with the Assyrians. Isaiah, in frustration, prophesies that God will send a sign to enlighten him: a maiden shall get with child and will name the male infant Immanuel, "God with us". What the prophet's hearers or, indeed, the prophet himself may have understood by his words remains, despite much exegesis, a riddle. Pass on to the real event: the accounts of Matthew and Luke are not a further development of the cult of the divinity and divine conception of the Pharaohs, or of the procreations of Zeus in Greek mythology, or even of the verses in Virgil's 4th Eclogue which speak of the birth, of a virgin, of a boy child – plausibly a hope and expectation that a figure, such as Augustus, will appear on the scene and put an end to the succession of wars and civil wars. No, this is the real thing; if God has not power over matter, all matter, then God is not God. The would-be believer feels braced by theologian Ratzinger's clear-cut conclusions. On the inextricable question of the virgin birth the German theologian Gisbert Greshake, a near-contemporary of Joseph Ratzinger, offers a radical explanation. But that is for high-level study.

Religious art, particularly the expressly devotional, may have lost traction, but one should still keep an eye out. The Bardini museum is a relatively small museum housed in a downtown villa in Florence that was once the convento church of a male religious order ministering to the sick (the Italian term applies to both convents and monasteries) and is home to the eclectic collection of the art dealer Bardini: just enough of sculpture, paintings, ornate woodcarvings, tapestries, etc to engage the interest without exhausting physically as would a full tour of the Uffizi  ̶  one comes out with some will still left for more.

Within is a painted woodcarving of a young woman in 15th century Florentine dress. The young woman is slight of figure and the floor-length dress sets off the grace of her body. The face, though, viewed directly from the front, appears quite bland, and disappoints. Why didn't the sculptor put a bit more animation into it? Moving around the figure clockwise to see the balance of the piece, the head looks down and to one side a little, to the right, and then it strikes you, actually with a shock, that there is a look of consternation on that other side of the face. The transition of expression from one side to the other is a triumph of art: it looks perfectly natural, and yet is uncanny. The inscription at the base explains everything: the Annunciation. The Florentine sculptor has expressed exactly the tale of the Gospel: Mary does not question the news, she registers only the human shock.

The census, which was for tax assessment purposes, was conducted over a period during the reign of Herod the Great and the governorship of Quirinius, and in two stages, property holders being required in the first stage to present themselves in the locality in which they held property. It may be assumed that Joseph, who was of the House of David in Bethlehem, was compelled to appear in Bethlehem because he held some property there. Thus Joseph Ratzinger.

The Jewish elite had been removed after the defeat by the Romans in 70 AD, and after Hadrian's defeat of the Bar Kokhba rebellion in 135 AD more deportations and enslavement followed, and the Romans built a cult temple to the Sumerian Tammuz-Adonis over the Bethlehem cave site, now revered by Judaeo-Christians, to obliterate it. Counter-theorists would have it that Sumerian cult worship at the site pre-dated its Christian association. However, cliff grottoes in the area around had been used as stables from time immemorial. The theologian Joseph Ratzinger insists that local tradition is often a more reliable and relied-upon source – as we in Ireland used to know.

And the star, and the wise men? Babylon, some 60 miles southwest of modern-day Baghdad, had been a centre of scientific astronomy. Aristotle recognised the work of the Persian astronomers, astrologers and truth-seekers. A small and elderly band of these still remained. In 7-6 BC a conjunction of Jupiter, Saturn and Mars occurred. Jupiter was associated with Marduk, the patron deity of Babylon. Already the unfortunate Bileam (Num 24,17) had prophesied an allegorical star which would raise a sceptre over Israel, and Tacitus and Suetonius mention the widespread expectation that a lord of the world would come out of Judea. The Babylonian seers would have made the connection and would, as a matter of course and of propriety, have enquired first in Jerusalem and at the court of Herod.

We have to forego the camels, bactrian or dromedary, of course: these were the trappings appropriate on the promotion of the wise men to kings; the ox and the donkey also, sadly, though these have Davidian associations. Nonetheless, gaudeamus!