In 1-L, Homer Kelley tells us that "In every athletic activity, success seems to be unquestionably proportional to the player's sense of balance and force -- whether inate or acquired.Off-balance force is notoriously erratic. The mechanical device has no balance problem but the human machine does, and mastery of the Pivot (Zone #1) is so essential for good Golf." [Bold and bold italics by Yoda.]
And he defined Zone #1 -- that would be Zone #1 -- as Body Control - Balance.
His Mechanical Checklist For All Strokes (12-3) lists 45 mission-critical alignments. The first item is "Stance-Balance" and the last is "Balance-Body Position."