Listen to me, please. Youre like me, a Homo sapiens, a wise human. Life, a miracle in the universe, appeared around four billion years ago, and we humans only 200,000 years ago. Yet we have succeeded in disrupting the balance that is so essential to life on Earth. Listen carefully to this extraordinary story, which is yours, and decide what you want to do with it.These are traces of our origins.At the beginning, our planet was no more than a chaos of fire, formed in the wake of its star, the sun. A cloud of agglutinated dust particles, similar to so many similar clusters in the universe. Yet this was where the miracle of life occurred. Today, life, our life, is just a link in a chain of innumerable living beings that have succeeded one another on Earth over nearly four billion years. And even today, new volcanoes continue to sculpt our landscapes. They offer a glimpse of what our Earth was like at its birth molten rock surging from the depths, solidifying, cracking, blistering or spreading in a thin crust, before fabling dormant for a time.These wreaths of smoke curling from the bowels of the Earth bear witness to the Earths original atmosphere. An atmosphere devoid of oxygen. A dense atmosphere, thick with water vapor, full of carbon dioxide. A furnace. But the Earth had an exceptional future, offered to it by water. At the right distance from the sun, not too far, not too near. The Earth was able to conserve water in liquid form. Water vapor condensed and fell in torrential downpours on Earth, and rivers appeared.The rivers shaped the surface of the Earth, cutting their channels, furrowing out valleys. They ran toward the lowest places on the globe to form the oceans. They tore minerals from the rocks, and gradually the freshwater of the oceans became heavy with salt. Water is a vital liquid.It irrigated these sterile expanses. The paths it traced are like the veins of a body, the branches of a tree, the vessels of the sap that it brought to the Earth. Nearly four billion years later, somewhere on Earth can still be found these works of art, left by the volcanoes ash, mixed with water from Icelands glaciers. There they are matter and water, water and matter soft and hard combined, the crucial alliance shared by every life-form on our planet. Minerals and metals are even older than the Earth. They are stardust. They provide the Earths colors. Red from iron, black from carbon, blue from copper, yellow from sulfur. Where do we come from?Where did life first spark into being? A miracle of time, primitive life-forms still exist in the golbes hot springs. They give them their colors. Theyre called archaeobacteria. They all feed off the Earths heat, all except the cyanobacteria, or blue-green algae. They alone have the capacity to turn to the sun to capture its energy. They are a vital ancestor of all yesterdays and todays plant species. These tiny bacteria and their billions of descendants changed the destiny of our planet. They transformed its atmosphere. What happened to the carbon that poisoned the atmosphere? Its still here, imprisoned in the Earths crust. We can read this chapter of the Earths history nowhere better than on the walls of Colorados Grand Canyon. They reveal nearby two billion years of the Earths history. Once upon a time, the Grand Canyon was a sea inhabited by microorganisms. They grew their shells by tapping into carbon from the atmosphere dissolved in the ocean. When they died, the shells sank and accumulated on the seabed. These strata are the product of those billions and billions of shells. Thanks to them, the carbon drained from the atmosphere, and other life-forms could develop. It is life that altered the atmosphere. Plant life fed off the suns energy, which enabled it to break apart the water molecule and take the oxygen. And oxygen filled the air. The Earths water cycle is a process of constant renewal. Waterfalls, water vapor, clouds, rain, springs, rivers, seas, oceans, glaciers. The cycle is never broken. Theres always the same quantity of water on Earth. All the successive species on Earth have drunk the same water. The astonishing matter that is water. One of the most unstable of all. It takes a liquid form as running water, gaseous as vapor or solid as ice. In Siberia, the frozen surfaces of the lakes in winter contain the traces of the forces that water deploys when it freezes. Lighter than water, the ice floats, rather than sinking to the bottom. It forms a protective mantle against the cold under which life can go on. The engine of life is linkage. Everything is linked. Nothing is self-sufficient. Water and air are inseparable, united in life and our life on Earth. Thus, clouds form over the oceans and bring rain to the landmasses, whose rivers carry water back to the oceans. Sharing is everything. The green expanse peeking through the clouds is the source of oxygen in the air. Seventy percent of this gas, without which our