The reason why I say you're right is because it is indeed mastering
templates and the recursive template-based processing model that is the
most important thing.

The reason why I say you're wrong is because I've got there - by
reflecting on what I'd been told, and by doing it.  The most important
thing, to me at any rate, is not that the problem is solved (although
that's a great relief), but that I truly understand the solution.  Why
it works.  The recursive model in fact.

For that reason I am extremely grateful to you and to everyone who has
contributed to this discussion.  If I'd had to pay for tutoring of this
quality I'd have become a great deal poorer.