"This I know today, but back then..."
What does this word order show? What's the rule?
"This I know today, but back then..."
What does this word order show? What's the rule?
In "This I know" there is no subject-verb inversion. Inversion would be This know I or better, as Jonathan says below: This do I know.
"this" is placed at the beginning of the sentence which is called fronting. The word in unusual position gets more emphasis or dynamic.
You should change your headline. Maybe: This I know. Inversion or fronting?
In order to be an inversion, it should have been written like this: "This do I know"... as a question. We use it to stress the feeling of saying the phrase, among other reasons.