Imagine, then, a cloud forest on a mountainside in Central America. Mushrooms grow from the horse-dung on the sides of a muddy path. I am following the path up to a volcanic crater. The volcano is said to be extinct; its crater houses a small lake. A thrush calls from one of the high trees I have no name for, trees that nourish a world of orchids and bromeliads and the quick creatures of the air. The light at ground-level is silvery, mossy, and the rain against my face is warm. Drops of it slither down the back of my neck. The trees are old, haunted by lichen, and occasionally they block the path. High up the mountain, the mud below my shoes turns to wet black ash. I have to clamber over a couple of fallen trunks in the half-light of the final stretch, the stretch that leads me to a viewpoint above the crater. Ferns ravel and unravel down the green slope. Tiny circles of airborne water, hundreds of them, appear in the lake below; ripple out; endlessly dissolve. I catch my damp breath watching them.