"The quarrels of popes and kings, with wars or pestilences, in every page; the men all so good for nothing, and hardly any women at all — it is very tiresome: and yet I often think it odd that it should be so dull, for a great deal of it must be invention. The speeches that are put into the heroes’ mouths, their thoughts and designs — the chief of all this must be invention, and invention is what delights me in other books.”
She's right. The men are often good for nothing and the women are usually missing. And she is also correct that the writing of history involves a lot of invention and yet it is usually boring. This is odd, as Catherine notes, because invention is often what makes other writing interesting.
Miss Tilney replies but, and I do so want to like her, sehe doesn't actually answer any of Catherine's criticisms:
“Historians, you think,” said Miss Tilney, “are not happy in their flights of fancy. They display imagination without raising interest. I am fond of history — and am very well contented to take the false with the true. In the principal facts they have sources of intelligence in former histories and records, which may be as much depended on, I conclude, as anything that does not actually pass under one’s own observation; and as for the little embellishments you speak of, they are embellishments, and I like them as such. If a speech be well drawn up, I read it with pleasure, by whomsoever it may be made — and probably with much greater, if the production of Mr. Hume or Mr. Robertson, than if the genuine words of Caractacus, Agricola, or Alfred the Great.”
But Catherine isn't concerned that the embellishments may be false, she is concerned that they aren't more interesting. We might begin to wonder if either of the Tilney's is paying all that much attention to poor Catherine.