What grammatical role does [an awful conviction that her discourse with the boy had been the main cause of the tragedy] play in this sentence?
NOTE: NOT A TEACHER
(1) This is the weekend. Maybe some of the teachers are busy but will answer you
come Monday.
(2) Your question so interests me that I ask permission to timidly advance a few
thoughts. If I am shown to be wrong, I shall immediately delete my post, which I am
often forced to do.
(3) A few random comments:
(a) I am not well-read. I have heard of Mr. Hardy, but I have never had any interest in
his novels or any novels. So I, of course, went to Professor Google and discovered
the pronoun "this" in your sentence refers to a suicide note left by one of the children.
(I had no idea that Jude the Obscure had such morbid scenes.)
(b) I then read some of the comments on the Web about your question, and one
term jumped out as the only logical explanation: absolute clause.
(c) Of course, people (such as I) who are not well educated can imagine anything.
So maybe (probably) I am imagining that this information from the great Otto
Jesperson may help us. In discussing such clauses, he writes:
[This kind of sentence] contains descriptive details and indications of
ATTENDANT CIRCUMSTANCES [my emphasis], generally added after the main part
of the sentence, and sometimes VERY LOOSELY CONNECTED WITH IT.
(i) One of his examples: She said her prayers at home, her heart full of love and tenderness.
(d) Am I totally crazy to think that it seems rather similar to:
At sight of the suicide note Sue's nerves utterly gave way, an awful conviction
that her discourse with the boy had been the main cause of the tragedy.
(In our analysis, we can forget the added clause "throwing her into ....")
(4) Final thoughts:
(a) Mr. Hardy's sentence is formal and very beautiful.
(b) The sentence is basically: At sight of the suicide note Sue's nerves gave way,
an event that threw her into a convulsive agony which knew no abatement.
(i) At the same time ("attendant circumstances"), there was an "awful conviction
that ...." It would be diagrammed as an absolute clause, having no formal
grammatical connection to the sentence but a very strong rhetorical/ logical
connection.