What Thoreau captures here is the stubborn chronology of growth—that prejudice isn't something we outgrow automatically, but something we must actively renounce, and that this renunciation loses none of its power whether we're twenty or eighty. Most people assume that time itself teaches tolerance, that we simply become less bigoted as we accumulate years, but Thoreau reverses this: the work is ours to do, always. Consider a person who spent forty years dismissing an entire group of people, then encountered one member of that group authentically—a colleague, a neighbor, a grandchild's friend—and felt their old certainties crack. That person hasn't wasted those four decades of prejudice; they've just finally begun the actual labor of thinking.