Jim Cook wrote:

To me the Key of this lesson is the word "MOTION".

As an example, with the horizontal hinge, the club after the take a way, starts moving towards impact. At the beginning, at any given moment the club face is open to the line but as the club continues to move the "MOTION" of the face is closing. It might be open but its "MOTION" is towards closing.

On the other side of impact the face is closed at any given instant but over time the face "MOTION" is still closing.

The same applies for the vertical hinge. The "MOTION" of the face is towards the layback.

Yep! The more I think about it the clearer it's becoming. I think ....