On the first page, there's a promotion/summary, and at the bottom, a box with a Publisher's Note.
This novel was originally published in 1968. In the intervening years the author has found portions of the novel which he believed could be improved; and so, he has rewritten these sections for this edition.
So now, I'm going to track down my other copy(I'm not sure if it also contains the changes or not) or another one, and try to find the changes. Anyone interested in the results?