Botanizing played a major role in Rousseau's life, second only to music, and perhaps not even second, during the last fifteen years of his life. Although he was not much interested when Mme de Warens pursued the subject with her steward-lover Claude Anet, he became smitten with botany during his exile in Môtiers in the 1760s, under the guidance of Neuchâtel friends such as d'Ivernois, Gagnebin, and Du Peyrou. It was Du Peyrou whom he startled by exclaiming, ‘Ah voilà de la pervenche’ (Confessions, vi), recalling his first glimpse of that flower during the halcyon days at Les Charmettes. In England he continued to collect plants and to press them in beautiful herbiers, some of which survive, and during his final decade in Paris he made frequent botanizing excursions in the countryside with Bernardin de Saint-Pierre. It was a way to know nature intimately without any intention to exploit that knowledge, and an opportunity for congenial companionship. ‘Errer nonchalamment dans les bois et dans la campagne,’ he says in the Confessions (xii), ‘prendre machinalement çà et là, tantôt une fleur, tantôt un rameau; brouter mon foin presque au hasard, observer mille et mille fois les mêmes choses, et toujours avec le même intérêt parce que je les oubliois toujours, était de quoi passer l’éternité sans pouvoir m'ennuyer un moment.' In addition to collecting plants, Rousseau acquired numerous botanical treatises, pondered the subject deeply, and wrote about it at length. Yet this important aspect of his life and thought has been largely neglected. That gap is now splendidly repaired in this learned and comprehensive study by Alexandra Cook, who previously translated Rousseau's botanical writings for the University Press of New England edition of the Works (2000). Her subtitle, The Salutary Science, points to Rousseau's conviction that studying plants in their natural setting was even more valuable for the soul than for the body (ever since his time in Annecy, he had been sceptical of the medicinal use of herbs). ‘Si l’étude des plantes me purge l'âme,' he declared, ‘c'est assez pour moi, je ne veux point d'autre pharmacie’ (Fragments de botanique). Jean-Jacques Rousseau and Botany is engagingly written and convincingly grounded in eighteenth-century scientific and cultural thought, and has no evident axe to grind, except for an entirely justified corrective to occasional claims that the reason Rousseau admired Linnaeus (which he did, but not exclusively) was that the sexual system of classification supposedly confirmed a reactionary view of gender relations. For a man who was persecuted and increasingly paranoid, botany represented above all, as Cook says, ‘a quest for freedom’ (p. 25). It was in that context that Rousseau wrote from Môtiers to Malesherbes, in a letter of 11 November 1764: ‘Il ne me vient jamais une idée vertueuse et utile que je ne voye à côté de moi la potence ou l’échafaut: avec un Linaeus dans la poche et du foin dans la tête j'espère qu'on ne me pendra pas.'