So often I see karate students using their arms as if their arms were disconnected from the rest of the body. The arms are moved by the waist. The waist moves, the arms and legs move. When this is done properly, there is very little effort involved in "blocking" (or receiving) the opponent's attack. But this is difficult to learn from a book or a magazine. Some things are better learned from a teacher.
"The root is in the feet, energy issues up through the legs, is controlled by the waist and is expressed in the hands and fingers."--Yang Lu-ch'an's Commentary to the T'ai-chi ch'uan Classic (Wile, p. 102).
How can you really see what's going on in this technique from Seipai unless you understand the movement of the millstone? It is difficult to learn how to step in towards the attacker, as the kata shows. "The circle of retreat is easy; the circle of advance is difficult," it says in the "Yang Family Manuscripts Copied by Shen Chia-chen" (Wile, p. 89). And it is especially difficult without first learning how the waist enters into all movement.
"The hands and feet work together and likewise knees, elbows and waist." From "Yang Family Manuscripts Collected by Li Ying-ang" (Wile, p. 36).
You can learn kata and bunkai--from watching or looking at videos or even from books and magazines--but you can't really learn how to move until you train with a partner. And even then, if it is not under the watchful eye of someone who knows these things, you won't get it. But once you do see this, then you will see the "hard and soft" in Goju. This is just good martial arts. It cuts across style lines.