But suppose I choose to walk, and someone obstructs me?" What part of you will they obstruct? Certainly not your power of assent? "No, my body." Your body, yes – as they might obstruct a rock. "Perhaps; but the upshot is, now I'm not allowed to walk." Whoever told you, "Walking is your irrevocable privilege'? I said only that the will to walk could not be obstructed.