I often get letters … from people who say … I never give credit to the almighty power that created nature. … I reply … “Well, it’s funny that the people, when they say that this is evidence of the Almighty, always quote beautiful things … orchids and hummingbirds and butterflies and roses.” But I always have to think too of a little boy sitting on the banks of a river in west Africa who has a worm boring through his eyeball, turning him blind before he’s five years old. And I … say, “Well, presumably the God you speak about created the worm as well,” and now, I find that baffling to credit a merciful God with that action. And therefore it seems to me safer to show things that I know to be truth, truthful and factual, and allow people to make up their own minds about the moralities of this thing, or indeed the theology of this thing.

It is difficult to conceive a grander mass of vegetation:—the straight shafts of the timber-trees shooting aloft, some naked and clean, with grey, pale, or brown bark; others literally clothed for yards with a continuous garment of epiphytes, one mass of blossoms, especially the white Orchids Caelogynes, which bloom in a profuse manner, whitening their trunks like snow. More bulky trunks were masses of interlacing climbers, Araliaceae, Leguminosae, Vines, and Menispermeae, Hydrangea, and Peppers, enclosing a hollow, once filled by the now strangled supporting tree, which has long ago decayed away. From the sides and summit of these, supple branches hung forth, either leafy or naked; the latter resembling cables flung from one tree to another, swinging in the breeze, their rocking motion increased by the weight of great bunches of ferns or Orchids, which were perched aloft in the loops. Perpetual moisture nourishes this dripping forest: and pendulous mosses and lichens are met with in profusion.

The interior of the rain forest is overwhelming in its complexity. There is not a bare surface anywhere. Branches are hung with curtains of mosses and sprays of orchids dangle among them. Tree trunks are filmed over with algae, studded by giant ferns, and wound about with vines. Ants travel in convoys across the ground and up the trees, and metallic beetles glint in sun-flecks on the forest floor. The forest itself is richly textured, stems embossed with every manner of protuberance, leaves ornamented by spines and pleats, scales and fringes. Long shafts of sunlight cut through the dark canopy and catch the flash of iridescent butterfly wings before diffusing in the vegetation below.

Thus, we have three principles for increasing adequacy of data: if you must work with a single object, look for imperfections that record historical descent; if several objects are available, try to render them as stages of a single historical process; if processes can be directly observed, sum up their effects through time. One may discuss these principles directly or recognize the ‘little problems’ that Darwin used to exemplify them: orchids, coral reefs, and worms–the middle book, the first, and the last.