Cytat: Bary123
To me both imply that writing either one or many books happened after I had met him
When I met him, he wrote a book.
Two readings are possible:
1. I met him and (later) he wrote a book. E.g. I met him, and I talked him into writing something.
2. He wrote a book and then we met. E.g., He invited me to talk about it)
When I met him, he wrote books.
Only one reading is possible: I met him when he was a writer (E.g. when he wrote books to earn his living.) N.B. it is a simultaneous reading. “He wrote books” denotes a state that he was in.
Compare: When I met him, he smoked. When I met him, he was 45 years old. When I met him, he drove a Jag.
Temporal states are homogeneous time intervals whose beginning and end points are de-emphasized as irrelevant or self-evident.