I'm stumped again, please help asap

[jessia]

The subject of this book is 19th-century heroes...
OR
The subject of this book are 19th-century heroes...

WHICH IS CORRECT?

If you turn the sentence round then I'm pretty certain that "19th-c. heroes are the subject of this book" is correct but does that have any bearing if you turn it round? In some inflected languages, see, they have the instrumental to sort this one out (the "real subject" - heroes here - are in the nominative and stay that way wherever you put them in the sentence, while their descriptor ("the subject of this book") goes in the instrumental or equiv. case).

So in my book (haha) it should be "are" but I've just been pulled up on it and want to check.

Ta, pedants dearies.

I would say is, but i have no idea why

is

or rewrite the sentence so that you are more comfortable with it

um - is - I think - because "the subject" is singular - and then you are quoting the name.

In your other examples the subject of the sentence is "19th c heroes" which is plural and therefore needs are .....

or another way "subject" is the noun, which controls the verb.

'is' correct, because the subject of the sentence is the word 'subject' which is singular. But agree that it sounds awkward. The fact that if you turn it round it becomes 'are' is irrelevant, because when you do that you are changing the subject of the sentence from a singular ('subject') to a plural ('heroes'). Rules from other languages that work differently from English also irrelevant, I'm afraid!

the subject is heroes of the nineteenth century sounds better

OK, I stand corrected - but at long last I know which is right!
Hurray, you pedantic MNetters are the best!