The book Karate Science includes the statement that:
One of the main goals of karate is to have the body postured in such a way as to allow a direct connection from the floor to the striking limb at the point of impact.
This is accompanied by the following diagram (with numbers rather clumsily added by me for clarity in the question):
However, I don't understand how any of these represent a "direct connection." Line 2 goes to the center of the body and only connects to the ground indirectly via 3, 4, and 5.
I also don't see how line 1 exists at all (except as an "imaginary line" brought about by the alignment of the arm and front leg).
Can someone explain this diagram to me? In particular, where the "direct connection" with the floor?