exposure

I have a low opinion of books; they are but piles of stones set up to show coming travelers where other minds have been, or at best signal smokes to call attention. Cadmus and all the other inventors of letters receive a thousand-fold more credit than they deserve. No amount of word-making will ever make a single soul to know these mountains. As well seek to warm the naked and frost-bitten by lectures on caloric and pictures of flame. One day's exposure to mountains is better than cartloads of books. See how willingly Nature poses herself upon photographer's plates. No earthly chemicals are so sensitive as those of the human soul. All that is required is exposure, and purity of material.

-- John Muir The Wilderness World of John Muir ed. Edwin Way Teale