Five feet under.

The humblest members of my garden I suppose are its worms. I seldom meet with them until the fall. Then, when bright blue days are cold but the soil is still warm, I see them everywhere under the decaying, thinning summer mulch.

We've been taught by Darwin to value worms. In fact, his book on worms is the foundation of the organic farming movement still growing today. But in 1840, when agriculture "was still a branch of chemistry," everyone thought worms were insignificant as they looked. Little escaped Darwin's massive powers of observation and thought, however. On a certain daily walk over years he thought he noticed the sinking of a layer of marl. But it hadn't sunk. In fact, worms had produced several inches of soil over it. Darwin saw the big implication: "I was thus led to conclude that all the vegetable mould over the whole country has passed many times through, and will again pass many times through, the intestinal canals of worms." This was the beginning of his forty-year study, formidable and charming, published in 1881: The Formation of Vegetable Mould through the Action of Worms with Observations on Their Habits.

The book charms me because the creatures are so small and Darwin's genius is so big. Of course they are not truly small because they are the foundation of a huge system which Darwin's observations helped the world to realize. When a scientist objected that worms were too small to do so much work, Darwin answered: he "generally undervalues small agencies and their accumulated effects." In this criticism of one short-sighted man, Darwin announced a principle: "Here we have an instance of the inability to sum up the effects of a continually recurrent cause, which has often retarded the progress of science, as formerly in the case of geology, and more recently in that of the principle of evolution."

And genius stops at nothing: "I became interested in them, and wished to learn how far they acted consciously, and how much mental power they displayed." He conducted experiments in perception with worms in two pots in his house. Can they hear? They proved "quite indifferent to the sound of the piano." But are they musical? Placed on the piano "and the note C in the bass clef [being] struck, both instantly retreated into their burrows." The same results with G above the line in the treble clef and C in the treble clef.

Other sensitivities? In experiments with smell, Darwin used onion and cabbage, "both of which are devoured with relish by worms." In fact, concerning cabbages, Darwin discovered that worms "can distinguish between different varieties." Here is an opportunity overlooked by seed companies to promote their vegetables not only for their prime but for their decay, in their consumption (with relish) at table and in the soil!

I have always liked worms, and Darwin showed me how deep our sympathies go, not only in matters of music and taste, but more intimately. Why, Darwin wanted to know, do worms often lie so near the surface that they are the numerous prey of birds? For warmth, he discovered. For "they often coat the mouths of their burrows with leaves, apparently to prevent their bodies from coming into contact with the cold damp earth." Very understandable. Worms are as fastidious as people. "It is said that they completely close their burrows during the winter." Exactly. What could be more reasonable?

All this leads to "what part worms have played in the history of the world." They aid in the decomposition of rocks; the softer ones, he discovered, passing through their gizzards. Particularly interesting is their role in "the preservation of ancient remains." Such research would be exotic here in North America, but is domestic and ordinary in England, where your neighbor might have a Roman ruin in his meadow, and you could calculate how much soil was brought up by worms to cover a mosaic floor fifteen hundred years old.

In fact, "in earth near an old Roman villa, which had not been disturbed for many centuries, a worm was met with at a depth of sixty-six inches; and this was in August." What a distinguished worm, so mortal in nature and so immortal in science! What did the worm feel when it was "met with" at such a depth and in such a season, in a place of antiquity where it might reasonably expect privacy and seclusion?

The worms in my garden are safer from unwonted meetings than worms in Roman villas because I disturb the structure of the soil so little as I garden. About worms I am curious but not scientific, content to honor them as the dear "small agencies," the "continually recurrent cause" of my soil's health. So our meetings are mostly, as they should be, in sympathy and good will of mind and soul.

Rosemary Deen, co-editor of Common-weal's poetry section, is the author of Naming the Light (University of Illinois Press).