Attributive appositive clauses disclose the meaning of the antecedent, which is expressed by an abstract noun. An attributive appositive clause is not separated from the principal clause by a comma.
Appositive clauses are chiefly introduced by the conjunction that, occasionally by the conjunction whether or by the adverbs how and why. They are not joined to the principal clause asyndetically.
He stopped in the hope that she would speak.(Dickens)
And then she had a nightmare conviction that she’d lost her sense of direction
and was going the wrong way. (Lindsay)
I have a presentiment that he is bringing trouble and misery with him into the
house.(Collins)
With his former doubt whether this dry hard personage were quite in earnest,
Clennam again turned his eyes attentively upon his face. (Dickens)
There was no reason why she should not read it (the book). (Hichens)
Thus to Cytherea and Owen Gray the question how their lives would end