What is it that constitutes the unity and identity of a living creature ? This is the fundmental question of biology. The recent sequencing techniques provide a completely new response to this question, notably thanks to the knowledge of whole genomes. Antoine Danchin establishes a clear picture of this important biological discovery. He shows in particular that, just like the boat of Delphi, life is beyond prediction, and at the same time has an infinite capacity to create the unexpected. Antoine Danchin is the director of the Department of Biochemistry and Molecular Genetics at the Institut Pasteur.