French farmers staged a dramatic protest against the European Union a few years ago by hauling sections of wheatfields that had been uprooted, and cattle and sheep, to the center of the Champs Elysòes. The police rushed to surround this sudden imposition of the countryside on the city, which disrupted business and traffic, and they braced themselves for fistfights between the citizens and the farmers. When the Parisians caught sight of the wheat and the animals, however, instead of reacting angrily, they ran toward them and began to stroll in the fields — lawyers, lovers, farmers, cops-dreamily together. For a few hours on that day, before they remembered who and where they were, all were happily back in the country.

Two conclusions may be drawn from this story, and both are correct. The fields of asphalt that ordinarily occupy the center of Paris may be called Elysian, but the name is simply a gloss, or an apology, applied to something that is nothing like Eden. Cities tend to create such places (find the tulips in New York City's Madison Square Garden) as a sort of nostalgic glance at the rural world they supplanted. If the farmers had not carted their bucolic protest to Paris on that day, the citizens there, like people in cities everywhere else, would have continued to conduct their life disconnected from anything in nature, much less paradise.

Yet the appearance of the instant countryside clearly and immediately reconnected them with a submerged world of sympathy long forgotten or ignored. This depth of feeling runs counter to the civilized, industrialized impulses of what Wordsworth called "getting and spending," and the tension between the two impulses characterizes most lives. On the first Earth Day of the new century (April 22), this is where we are — running hard to catch up with our heady commercial present and our future in cyberspace and at the same time capable of being called back, at the drop of a wheatfield, to a life that connects us with all life.

However frenetically we get and spend, an attachment to the natural life of the planet remains fixed in our system. Environmentalists sometimes complain that the memory of this attachment is buried too deep, though it continually surfaces, not only in names of places but also in turns of language that have no meaning in modern experience but are kept alive, nonetheless, like verbal souvenirs — horsepower, stream of consciousness, it's a jungle out there. One cannot think of a single composer, painter or writer who has not tracked at least one major inspiration to a bird, a tree, a rose. People automatically lose themselves in wordless reverence at the sight of a curlew or a silver cloud of anchovies or at the mournful wail of howler monkeys. Or they stare dumbly out at oceans, as if longing for their microbial past.

Everything connects: the hard animals with the soft; the tigers with the jellies; the fly with the cutthroat trout with the fisherman. In the rain forest, the understory palm trees use branches growing out of their trunks to make baskets that become compost machines for falling leaves, which keep the trees alive. In the ecosystems of the tropics, termites eat and digest cellulose, a major component of plant tissue; without the decay of cellulose, the system would die trapped in dead wood and stems. Hidden worlds connect to the things that hide them; within the bark of a redwood lies moss under which are toads and insects. Tide pools connect with unfathomable seas, which connect with our chromosomes.

For the world on Earth Day, the matter is less esoteric and more urgent. There is no concern these days more important than the environment — not gun control, violence in the media, campaign-finance reform, not even poverty, war, refugees or the curing of fatal diseases. Americans are about to be swept up in a presidential election campaign in which candidates will rant about such issues, all of which are dwarfed by the need to protect and enhance our habitat. We are not even aware of the full dimensions of the problem. Fewer than 2 million species of animals, plants and microorganisms have been identified. Yet tens of millions more may exist — in oceans, rain forests and everybody's gardens. The benthic, or bottom-dwelling, plants and animals in the oceans represent the least-known ecosystem on Earth.