"To go from point A to point B. If we divide that by one million we will pass through every fraction of that million. At some point our weight will be equally divided between the front heel and the ball of the rear foot."
This is a meaningless argument without taking into account the rather complicated meaning of "weight" in a dynamic system, where smooth movement can easily involve periods where the total force is greater than or lesser than the equivalent of gravity acting on the body mass.
"The knee will not be bent."
This is the far more interesting failure of observation - the fact is, that for skilled dancers, the front leg is generally not straight at the extreme of a a fully lowered step-one action, because if it were it would stick out too far out in front of the body movement. Many lesser dancers do teach the idea that one should have it straight at mid-stride. But that's just not what you see the best doing, for the very good reason that putting a leg far out in front of your body movement is counterproductive to the joint goals of smooth movement and clean partnering. Instead, what you will see the best dancers doing is keeping their body noticeably closer to the front leg than the rear, with the obvious result that the front knee doesn't straighten as much as the rear one does.
It's very easy to mistake swinging the moving leg for generating body movement. Gaining skill as a dancer is largely about outgrowing limiting habits like that, and the more masterful dancers have refined this to a greater degree than the others.
"Or this. In the Foxtrot rise at the end of the step as in a Featherstep."
Don't make the mistake of taking that farther than the very specific and narrow meaning of "rise" to which it refers. Everyone can see that the body smoothly and continuously gains altitude up until about when the feet pass at the end of step two, then begins smoothly losing altitude thereafter and all the way through step 3. The "rise" and fall given in the book is only one component contributing to the more musically and physically important concept of a gentle and continuously connected flow of up and down.
