“Do we see the hundred-thousandth part of what exists? Look here; there is the wind, which is the strongest force in nature. It knocks down men, and blows down buildings, uproots trees, raises the sea into mountains of water, destroys cliffs and casts great ships on to the breakers; it kills, it whistles, it sighs, it roars. But have you ever seen it, and can you see it? Yet it exists for all that.”