Covering almost 8 percent of the earth's terrain, lichens are living beings which are familiar to everyone, known to no one. They are one of those organisms that seem to offer nothing to hold our gaze. But the more time we spend with lichens, the more they reveal their beauty, their mysteries and their strange power of attraction. Part-algae and part-fungus, lichens call into question our customary ways of classifying forms of life, and allow us to conceive of an ecology that is no longer based on distinctions between nature and culture, urban and rural, competition and cooperation.

The result of several years of investigation carried out on several different continents, this remarkable book offers an original, radical, and, like its subject matter, symbiotic reflection on this common but mostly invisible form of life, blending cultures and disciplines, drawing on biology, ecology, philosophy, literature, poetry, even graphic art. What if lichens were at the heart of some of the most pressing and topical questions of our day? Does the fact that they can live everywhere, even in very harsh environments, that they persist when almost all other traces of life have disappeared, mean that, despite their fragility, lichens are a force of resistance?