Every move in Taiji is a downward move. This begs the question how many moves can you make before you are sitting on the floor? Master Chen says if you can make every move a downward move without going down then you have got it. The key is that downward is a rotation. Thisis called sinking.
Take the movement in Fetching Water: the body appears to go physically downward but the person does not actually go up and down. What’s actually happening is ain the joints. To demonstrate this Master Chen sat down on the steps with a cylindrical water bottle pressed between his knees; the top of the bottle pressing into one knee and the bottom pressing into the other. “Imagine a line on the top” he said, then he rotated the cylinder 180 degrees down. “Do you see where the line is now?” It was on the bottom. “This is rotation.” To clarify he explained that in relation to the original position the line was on the bottom, but the cylinder had never moved, it only rotated. This action is sinking. Sinking is not going down, it is a rotation.