Take a course in good water and air and in the eternal youth of Nature you may renew your own. Go quietly, alone no harm will befall you.

The speaker urges a deliberate “course” of immersion in elemental nature—clean water, fresh air, and the perpetual renewal visible in wild landscapes—as a remedy for human fatigue and spiritual depletion. “Eternal youth of Nature” frames the natural world as continuously self-renewing, offering a model and medium through which a person can recover vitality. The second sentence counters common anxieties about solitude and wilderness: moving “quietly” and alone is presented as safe and restorative rather than threatening. Overall, the quote expresses a characteristic Muir-like faith that communion with nature is both morally and physically regenerative, and that solitude in the outdoors can be a form of healing discipline.