I like making large pronouncements on large issues of English, don’t I? But let’s look at a small one: the words but and yet.

These are useful words, but almost unnoticeable ones. In their commonest use, to mean however, they signify nothing, describe nothing, modify nothing. We tend to treat them as identical. But but is not quite the same as yet. Nor yet is yet the same as but.

The difference is subtle, one of those countless subtleties that distinguish good English from English that is perfectly acceptable but routine. But is a broad-spectrum word, yet is a narrower one. For example: he’s a magnificent batsman, but no great bowler; the tourists visited Agra, but not Jaipur; India and Pakistan are neighbours, yet their leaders seldom meet; he has an IQ of 170, yet he can’t add 2 and 2 to make 4.

You could use but in all four sentences, but yet would look odd in the first pair. Why? Because yet always implies — as but need not — that the phrase after it is in some way contrary to what you’d expect from the phrase before. There’s no reason to expect a good batsman to be a good bowler, nor that tourists will visit Jaipur just because they’ve been to Agra. But you do expect that leaders of neighbouring countries will meet each other quite often, and that a genius will be able to add two and two.

How has the distinction arisen? There’s no clue in the two words’ etymologies. Both, any dictionary will tell you, come from Old English: but from a word meaning outside or without, while yet comes from one with a sense of time, as in today’s German jetzt, meaning now. These origins are reflected in the two words’ many other, quite distinct uses. But tends to mean except, as in no one but Gandhi could have done it; or it never rains but it pours; or there but for the grace of God go I. Yet carries the sense of time in phrases like he hasn’t arrived yet, though it is hard to see it in nor yet... or a yet fiercer rebuff. However, none of this helps to explain why but and yet are so subtly distinct in their however sense.

My own favourite dictionary likes to draw still subtler distinctions within the whole family of such words: but, yet, however, still, nevertheless (and nonetheless, if you choose to spell it as a single word). Its distinctions are questionable. But it’s true that all these words other than but do tend to imply slightly more than mere contrast with what went before. They add an element of surprise. The contrast is with something you might expect but you’d be wrong. For example: we’ll go on foot, however (or nevertheless, still, yet) we’ll be there before nightfall.

Why English has developed all these words to say very much the same thing is a mystery. Why yet (like still) should have grown from its sense of time into one of contrast is equally unclear. And why yet and but should have developed their subtly different usages is less clear still. I’ve met no scholarly explanation. But (or yet) a distinction there is — and one well worth observing.