English summary: In this book, Dogen, the XIIIth century Japanese Zen master, addresses his disciples. In his first address he tells them: Buddha alone knows Buddha: complete combustion. That is to say, Truth alone knows Truth, perfect har-mony. When the Truth is known an overwhelming event called awaken-ing occurs. Yet, Dogen tells us that we are always and already awakened. This re-cognition takes place with and in this world, "the entire universe", which is none other than our true "body". In his second address, Life-death, he says to his disciples that birth and death, "life-death", are both the extreme events of our journey and the very dynamism of our "body", the universe. Samsara is nirvana. Let the world accomplish itself and let us accomplish our-selves with it. French description: Dans ce livre, Dogen, maitre zen japonais du XIIIe siecle, s'entretient avec ses disciples. Il leur dit d'abord : Seul Bouddha connait Bouddha : combustion totale. En d'autres termes, seule la Verite connait la Verite : harmonie parfaite. Quand la Verite est connue, se produit cet evenement bouleversant appele eveil. L'eveil est toujours et deja la. Cette re-connaissance a lieu en ce monde, "l'univers entier" et avec lui. Il n'est autre que notre "corps" veritable. Il leur dit ensuite que naissance et mort, "vie-mort", sont non seulement les evenements extremes de notre traversee, mais aussi le dynamisme meme de notre "corps", l'univers. Samsara est nirvana. Laissons le monde s'accomplir et accomplissons-nous avec lui.