On Tuesday at my mother's funeral we sang "Abide With Me". It's a popular hymn for funerals, possibly because people like the line "Where is death's sting? Where, grave, thy victory?"; but as we sang the fifth verse (you can see the lyrics here) I couldn't help noticing a syntactic point.
No, don't be shocked that syntax could be on my mind on such an occasion. A linguist's brain does not cease making linguistic observations on entering a crematorium chapel. As I recently explained in a piece over at Lingua Franca, linguistics is not a task that one takes up only as necessary; it is more like a kind of affliction, making the afflicted person incapable of not noticing points of interest in linguistic material. Here is the stanza that I could not help noticing:
Thou on my head in early youth didst smile,
And though rebellious and perverse meanwhile,
Thou hast not left me, oft as I left Thee.
On to the close, O Lord, abide with me.
Perhaps you can immediately see what struck me about the first sentence (the first three lines)?
It's a dangling modifier! The part that says "though rebellious and perverse meanwhile, Thou hast not left me" has an initial adjunct, the preposition phrase though rebellious and perverse meanwhile, in which the coordination of predicative adjectives, rebellious and perverse needs a target of predication. Who is being claimed to have been rebellious and perverse?
We naturally look first to the subject of the main clause in these cases: when we read Though young, Susan is highly qualified we understand that Susan is being claimed to be young.
But when we look to the main clause subject in the lines above, we find Thou. It makes no sense to tell God, "You have not left me, though [you were] rebellious and perverse." That cannot possibly be the right meaning. And so we look back and forth for some other possibility that could permit a suitable noun phrase meaning to be borrowed.
Not much is on offer, but finally we (unconsciously) hit on the phrase on my head, where my, though syntactically functioning as a genitive determiner, is a first person singular pronoun. If we plug in that meaning we get something conceivably sensible: "Thou on my head in early youth didst smile, and though [I was] rebellious and perverse meanwhile, Thou hast not left me, oft as I left Thee."
Or in modern English with less tortured constituent order, "You smiled on my head in [my] early youth, and though [I was] rebellious and perverse meanwhile, you have not left me, despite the fact that I often left you."
The passage in question is a clear example of the so-called dangling modifier. Look at a modern version again, without the bits of bracketed help:
You smiled on my head in early youth, and though rebellious and perverse meanwhile, you have not left me.
There are actually two unclarities in the sentence: first, whose early youth are we talking about? And second, whose rebelliousness and perversity? It's really a strikingly bad piece of writing.
That doesn't mean it's ungrammatical. My personal view about the dangling modifier error is that it is not actually a syntactic mistake. I think the grammar of English permits nonfinite clauses and predicative constituents to be used as adjuncts quite freely, and it is a matter of style and consideration for the reader that the writer should try to ensure that they will be properly understood.
It is unfortunately easy to write sentences in which the intended meaning will not be easily understood, either because there is no conveniently located noun phrase to permit the predication to be interpreted at all (Afraid of flying, there was nothing that could be done), or because the most immediately accessible noun phrase makes for a crazy interpretation and thus cannot possibly be the right one (Afraid of exhausting herself, John asked if perhaps someone could help Mary with setting things up).
Don't write like this. Yes, that's prescriptive, but it's not bad prescriptivism; it's good advice. Make sure when you use a nonfinite clauses or predicative constituents as adjuncts that it is instantly clear on first reading how they are to be understood.
Henry Francis Lyte didn't do that when he wrote "Abide with me". But we all tend to forgive older English usage for all sorts of sins, wrongly imagining that the bad grammar and style is all a feature of the modern world and things have only been going to the dogs in the last few years. The situation is very different. There are famous examples of dangling modifiers in Shakespeare. ("'Tis given out that, while sleeping in mine orchard // A serpent stung me" says the ghost of Hamlet's father, and he doesn't mean that the serpent was sleeping.) We give a free pass to authors of earlier centuries, but go ape when we see the same sort of carelessness in a business memo or newspaper article today.