The great collection debate

I put a copy--draft--of a chapter from my next book on the website wwww.animalsi.com. The chapter is on "collection" of the horse. Collection is a term/concept that is really misunderstood--one author called it "mythunderstood--and as such it is difficult for someone to know what to believe it is.
There are those people who go back to the classics and read them to gain a better understanding of it. Throughout my riding career, in taking lessons, I've been told that I/we need to "collect" the horse. Often this was accompanied by an indication that the horse should "round" its back to indicate it was collected. It didn't seem to matter that the horse may be round behind while tight along the top line as in some champion cutting horses I watched on TV last week.
In my research on what collection means anatomically, I've come across three main, what I'm calling, themes: 1. the topline, 2. the bottom line and 3. the shoulder freedom theme. I've always been a proponent of the shoulder freedom theme and designed my work around this. This theme has been backed up by research by Dr. Hillary Clayton as has the first theme. What I've come to conclude is that collection occurs through the interaction of these three themes.
I'll write more on the website, so I can add some illustrations and animations. If you get a chance to visit and read the chapter, let me know what you think.