There's an interesting article by Victoria Myers that talks about Richardson's participation in the letter-writing manual trend ("Model Letters, Moral Living: Letter-Writing Manuals by Daniel Defoe and Samuel Richardson"). Richardson's most famous manual, Familiar Letters, provides models for domestic letter-writing, and each letter regards a very specific domestic instance (one letter is entitled "To a Father, against putting a Youth of but moderate Parts to a Profession that requires more extensive Abilities").
The interesting thing about Richardson's manual is not the way in which it seeks to create some standard for letter-writing, but how it sees letters as a way of promoting moral improvement in the recipient(s) of the letters. This is effected through a very precise use of language. For instance, Richardson has specific rules about what kinds of passions can be expressed (and to what degree they can be expressed) in different situations so that the moral message is not obscured.
Anyway, this article made me think about the extent to which Clarissa might be a giant letter-writing manual. I think the introduction to our version of Clarissa mentions that Richardson was commissioned to write Familiar Letters (or some other letter-writing manual, I'll have to look it up), and that it eventually evolved into Pamela. I think our attention to language in this class reveals that Richardson still has some of those letter-writing manual concerns in mind, in terms of how precise one's language must be to convey one's point, etc.
Here's a link to Myers's article if you want to read it: