I think the stillness refers to the idea of keeping your eyes steady on a target, even if your head or body is moving around. I'm a competitive bowler, and you

I think the stillness refers to the idea of keeping your eyes steady on a target, even if your head or body is moving around. I'm a competitive bowler, and you use a small spot on the lane about 15 feet out (there are arrows to help you target) as your visual focus. When you watch the best bowlers, although they are walking to the foul line, so their arms and legs are moving, their head and eyes are basically motionless, as they are keeping their eye on the target throughout the approach and after the release of the ball. In fact, coaches will tell you to watch your ball roll over your target and not lift your head up for another second after that, as a way of enforcing the "eye on the target" concept.