James captures something more unsettling than simple modesty here—he's describing the fundamental condition of meaningful work itself, not just its humble execution. We cannot see the full consequences of our labor, which means we must act despite uncertainty, guided only by our present capabilities and conscience. A teacher grading papers late at night doesn't know which marginal note will resurrect a failing student's confidence five years hence, yet the work demands completion anyway. The quote's power lies not in celebrating small efforts, but in insisting that darkness is no excuse for paralysis.