The structure is more or less alternating chapters, with a introspective musings by the author on the nature of walking (and of walking in nature; urban walking gets short shrift) being followed by a biographical sketch of writer or philosopher (usually, though also Gandhi).
Overall, the first half or so of the book is the best. The first author delved into deeply is Friedrich Nietzsche and his story of the German philosopher’s mental and physical decline was downright moving and his deftly illustrated the importance of (usually solitary) long walks in the countryside to his process and mental well being. The section on Rimbaud was almost as good. The one on Kant provided an interesting counterpoint to Nietzsche. The one on Rousseau… was okay. I said he gives short shrift to cities (the walking about which Gros philosophizes is more hiking than a stroll) and the chapter on, ostensibly, Baudelaire, the great flâneur, contrives to be mostly about Walter Benjamin and is not terribly respectful of that mode.
But shouldn’t criticize too much. It is not philosophy, in an academic sense, but a brisk read. Perfect, perhaps, to take on a long, silent walk. Silent because, as Gros writes, ‘But above all, silence is the dissipation of our language.’