In 1941 the BBC gave a middle-aged Oxford don fifteen minutes of airtime and asked him to explain Christianity to a country being bombed. He came back four times, and what he said over those broadcasts became this book.
Lewis begins somewhere unexpected: with two people quarrelling. Listen to any argument, he says, and you will hear both parties appealing to a standard they expect the other to already acknowledge — that's not fair, you promised, how would you like it. Nobody says my morality differs from yours. They argue as though a real law were in the room with them. Lewis spends the first part of the book asking what that law is and where it could have come from, and he does it without a single appeal to scripture or authority.
The mere in the title is doing precise work. Lewis set out to explain what has been common to nearly all Christians at all times, deliberately leaving the disputes between denominations to the denominations. He compared it to a hall with doors leading off it: the hall is a place to wait and to warm yourself, not a place to live.
The prose is the reason it has never gone out of print. Lewis was a literary scholar writing for people who had no theology and no patience, and every abstraction is anchored to something you can picture — a fleet of ships, a tin soldier, a man who thinks himself decent because he has never been seriously tempted.
Read it beside Chesterton. Lewis said The Everlasting Man was one of the books that undid his atheism, and the debt shows: the same habit of turning a familiar thing around until it looks strange again, the same refusal to be solemn about serious matters.
