"En" in "Sa voix restait si calme et naturelle que mon exclamation m’en parut d’autant plus ridiculement emphatique"

Question

This question is on the following sentence, from chapter 7 of La porte étroite by André Gide.

Sa voix restait si calme et naturelle que mon exclamation m’en parut d’autant plus ridiculement emphatique.

QUESTION

I am trying to account for en and have come up with the following ideas. Please let me know if they are right. Where they are wrong, please tell me what I should have thought instead.

1. A d’autant plus + adverb construction may be completed with either a pour-phrase or a que-clause supplying a cause, reason or occasion. (This would be rather like so much the more + adverb completing with a for, now that or as.)

2. En in the Gide sentence results from (represents or means) pour + le. From this I should draw the lesson that en may unpack into pour + something, and not always de + something.

3. Le, or the 'thing' in en, in this case would be the whole preceding clause, i.e. Sa voix restait si calme et naturelle.

Answer 1

Your third option seems all right.

Sa voix restait si calme et naturelle que mon exclamation m’en parut d’autant plus ridiculement emphatique.

Without changing the whole structure, you could reconstruct a de-headed complement:

Sa voix restait si calme et naturelle que mon exclamation me parut de ce fait d’autant plus ridiculement emphatique.

But of course, you could also reverse subordination, getting a completely different structure for approximately the same meaning:

Mon exclamation me parut d’autant plus ridiculement emphatique que sa voix restait si calme et naturelle.

Answer 2

1. I can see d'autant plus + adverb + que, but not d'autant plus + adverb + pour. Could you give an example with pour that we could look at?

2. I don't think a priori that this en has to do with a pour-phrase or que-clause. I think it only stands in for Sa voix restait si calme et naturelle.

3. Yes.