Emerson isn't merely cheerleading for confidence—he's suggesting something stranger and more muscular: that self-trust operates like a tuning fork, resonating with others at some frequency beyond argument or persuasion. Notice the word "iron"—trust isn't delicate or sentimental, but something hard and unbreakable that compels response. When you've watched a genuinely self-assured person enter a room, you've felt this: not through their words, but through an almost physical certainty they emanate. That electrician who knows his trade doesn't convince you of his competence through talking; you simply feel it, and your doubt quiets to silence.