Tom Sutcliffe: This holy child needs a crib sheet

I learnt some new words last week, which is always a pleasing thing – though I doubt that I'm going to get a lot of opportunities to drop them into conversation. I can't really imagine a social situation – outside of the Royal Academy's Byzantium exhibition – when I might find myself needing to refer to "the Virgin hodegetria". And even if I did I think the chances are pretty slim that I would encounter anyone who knew what it meant. If you're curious, incidentally, it's the name you give to a particular iconographic representation of the Virgin Mary. "Hodegetria" is Greek for "one who shows the way" and it refers to paintings in which the Virgin is shown gesturing to the Christ child on her lap, in effect telling the viewer that this is their one-stop-shop for salvation.

And that wasn't the only novel term of art I came away with. Take "koimesis" as another example – a phrase that refers to "the falling asleep" (or the death) of the Virgin and which also appears in titles in its latin form, as "dormition". Or "anastasis" – which literally means a rising up or a removal but which is used in Byzantine art to describe an image showing Christ harrowing hell, that theological jail-break when the saviour descended into the inferno to release those deserving of parole (and, presumably, leave countless others behind to suffer eternal torture).

And when I say that I learnt these words I mean precisely that, because the Royal Academy wasn't offering a lot of help. It's possible that the audio guide helpfully explicated all these terms, but I don't usually use those anyway and the labels certainly weren't giving anything away. There is, as it happens, a useful glossary in the catalogue, which explicates all these terms and several others. But consulting that hefty and glossy volume would have been slightly impractical while actually touring the show. As a result it was only later, after trawling the internet for explanations, that the light of understanding dawned, a fact that may have amplified the peculiar feeling of claustrophobia that this exhibition induced in me.

The problem is the religion, I think. Not the Greek Orthodox church in particular, the faith which many of the objects derive from, but religion in general, and the armoury of concepts that may not be explicitly designed to separate priestly class from layman, but which certainly have that effect when encountered en masse. To enter the Royal Academy exhibition spaces at the moment is to enter a cultural space that is concertedly indifferent to the world from which most people have arrived. The pictures here are not windows on space we all share, but portals into a transcendent place, directing us somewhere else altogether. There are some exceptions to this generalisation: a child's tunic from Egypt; some metal spoons which hint at earthly, and earthy, life. But these signs of common human experience are few and far between – and vastly outnumbered by objects whose natural home is a sacred inner sanctum, and which seem to turn inward, away from outside influences, bent in devotion over their own hermetic mysteries.

They are objects that badly need a bit of evangelism, but they don't get it. Because the piety that virtually all of these objects express (and on which I'm inclined to think they depend for their effect) is overlaid by another piety – that of the academic museum show, in which the relic is an object of unquestioned veneration and a faint air of vulgarity or blasphemy attaches to the very idea of explanation. Don't ask too many questions, simply believe – or venerate. I wasn't able to do it myself, and it would have been nice to have some really meaty labels to read as an alternative.

Who ignored the rules?

One of the irritating things about the Brand/Ross scandal has been listening to the BBC's ideological enemies leap on it as evidence of systemic rot in the corporation. I present a programme for Radio 4 once a week and, every week, an editorial figure sits in on the recording to vet its contents. Indeed, an occasionally irritating degree of care is taken over elements that might conceivably offend listeners. Somehow I doubt that I happen to be working in the only department in the building that actually adheres to the BBC's required practice in this regard. Regrettably, I don't earn £6m a year, so I can't authoritatively say what that does to the balance of power between broadcaster and producer. But it isn't that the BBC can't be bothered to lay down rules. It's that for some reason individuals chose to ignore them.

I'm always tempted to skip the first chapter of a biography, since I generally find it difficult to muster much interest in a subject's great-grandparents. I often sense, too, that biographers are just going through the motions at this point – filling in the genealogical tables because they know it's expected of them. The opening sentence of Ian McIntyre's new biography of the 18th-century diarist Hester Thrale impressively finesses the problem: "She could be a bit of a bore about her family," it reads. At a stroke the pedigree becomes anything but boring; we want to know why Hester's ancestors inspired her to jeopardise her reputation for wit. We're also reassured that the author isn't blind to his subject's faults, even if he's likely to be affectionate about the personality they represent. All done, very neatly, in just 11 words.