There were two things going on: 1) I had already established in my own mind where I wanted to go with the next series and having James around as a Grey Eminence would have complicated matters. He had had an amazing life and it was time to bid him good-bye.
Before success comes in any man's life he's sure to meet with much temporary defeat and perhaps some failures. When defeat overtakes a man the easiest and the most logical thing to do is to quit. That's exactly what the majority of men do.