Should Authors and Illustrators Be Allowed to Collaborate?

This past Saturday I held a Children’s Literary Salon here in Evanston on the topic of writing children’s books, common mistakes made by newcomers, where to go for advice, etc. (you can view the talk in its entirety here). At one point I asked my panel to say one piece of advice they might offer to people who want to write children’s books. And in time, one person mentioned (as I had hoped that they would) that it is always a mistake to send in a manuscript with an illustrator already in plac...