inversion: you are -> are you

[Abstract Idea]

"In few other professions are you required, each and every day, to weigh so many competing claims ... " (from an American book)

What is the grammatical reason for the inversion above - "are you" instead of "you are"? I feel it sounds quite right, but I cannot explain it satisfactorily. Ordinarily we use the inversion in interrogative sentences, but here we have an affirmative one.

If I changed the sentence a little bit to:
"In few other professions is one required ... " would it be also correct? and is such inversion mandatory?

[Soup]

"In few other professions are you required, each and every day, to weigh so many competing claims ... " (from an American book)

What is the grammatical reason for the inversion above - "are you" instead of "you are"? I feel it sounds quite right, but I cannot explain it satisfactorily. Ordinarily we use the inversion in interrogative sentences, but here we have an affirmative one.

It could be that the adverbial phrase In few other professions is similar to negative frequency adverbs (never, scarcely, hardly, ever, seldom, rarely) and the reason for the subject-aux inversion.

If I changed the sentence a little bit to:
"In few other professions is one required ... " would it be also correct? and is such inversion mandatory?

"Yes" to both questions.

[Abstract Idea]

It could be that the adverbial phrase In few other professions is similar to negative frequency adverbs (never, scarcely, hardly, ever, seldom, rarely) and the reason for the subject-aux inversion.

"Yes" to both questions.

Okay Soup, thanks! If I understand it right in affirmative sentences this inversion cannot occur, for example:
"In many other professions one is required ... "

[Raymott]

Okay Soup, thanks! If I understand it right in affirmative sentences this inversion cannot occur, for example:
"In many other professions one is required ... "

Yes, you understand it right.