It happens that lately I have been reading old and new novels alternately — one from the 1940s and then one from 2004 and then another from the 1930s and so on. If you read like this, you cannot help but notice the difference in what the authors expect of the reader.

Novels from the early 20th century assume that the reader will be familiar with Shakespeare, the Bible, the most popular works of the ancient Greeks, a smattering of common words from several European languages, and major people from history, as well as some basic terms from music and the other arts. Modern novelists don’t assume anything of the kind. They expect us to recognise popular brand names, but that is about it.

And this is true not only of folks like Michael Innis and Edmund Crispin, whom you might think of as rather highbrow writers anyway, but of Agatha Christie and her ilk as well.

One school of thought is that this is an indictment of modern education. There may be some truth in that. There is more and more emphasis on skills rather than content in children’s education, and more and more emphasis on vocational training at the college level. The idea of being an educated person, and that there is some value to being educated rather than trained for something, may be an outmoded idea.

It may also be that literacy was simply not as widespread in those days. Perhaps a novelist could assume that only educated people would be reading his or her books. Nowadays, just about everyone can read, so novelists might have to write with that awareness.

A third possibility is that there is no longer a body of knowledge that can be accepted as what people ought to know. That is, there is so much information running around loose nowadays, that no one can be expected to know all of it. So the idea of some set of information being something everyone can be expected to know might be an outmoded one. Educated people might conceivably have non-overlapping sets of knowledge, and yet still be educated.

I can’t quite believe that last one. I find myself startled when people don’t know quite ordinary things, don’t you? Like a recent caller who wanted a poster of “the spectrum from black to white,” or a man I heard talking about “Gertrude Steinem.” I mean, don’t you sort of wonder where they grew up?

My husband grew up in a completely different place from me, so I would not expect him to be conversant with Shakespeare any more than he would expect me to be able to build a house or to sing the traditional opera of his country. And maybe people younger than I are in a sense growing up in a completely different place, too, and are no longer expected to know who Pepys was.

So they can’t read Michael Innes. That’s a bit of a loss, isn’t it?

With house guests expected tomorrow, I must now give up these abstract speculations and get to my domestic work. I must clean and bake and plant things.The temptation to plant things at this time of year is enormous. You have to remind yourself that they will grow, and have weeds, and require harvesting and processing and storage and so on, or you can get carried away. Or at least I can.