Read it through once

“Precisely: I see you do. I see genuine contentment in your gait and mien, your eye and face, when you are helping me and pleasing me—working for me, and with me, in, as you characteristically say, ‘_all that is right_:’ for if I bid you do what you thought wrong, there would be no light-footed running, no neat-handed alacrity, no lively glance and animated complexion. My friend would then turn to me, quiet and pale, and would say, ‘No, sir; that is impossible: I cannot do it, because it is wrong;’ and would become immutable as a fixed star. Well, you too have power over me, and may injure me: yet I dare not show you where I am vulnerable, lest, faithful and friendly as you are, you should transfix me at once.”