He spent four years at the Geneva Academy, studying science and law according to his father's wishes. In 1798, he moved to Paris after Geneva had been annexed to the French Republic. His botanical career formally began with the help of
René Louiche Desfontaines, who recommended de Candolle for work in the
herbarium of
Charles Louis L'Héritier de Brutelle during the summer of 1798. The position elevated de Candolle's reputation and also led to valuable instruction from Desfontaines himself. de Candolle established his first genus,
Senebiera, in 1799. De Candolle's first books,
Plantarum historia succulentarum (4 vols., 1799) and
Astragalogia (1802), brought him to the notice of
Georges Cuvier and
Jean-Baptiste Lamarck. de Candolle, with Cuvier's approval, acted as deputy at the
Collège de France in 1802. Lamarck entrusted him with the publication of the third edition of the
Flore française (1805–1815), and in the introduction entitled
Principes élémentaires de botanique, de Candolle proposed a natural method of plant classification as opposed to the artificial
Linnaean method. The premise of de Candolle's method is that taxa do not fall along a linear scale; they are discrete, not continuous. Lamarck had originally published this work in 1778, with a second edition in 1795. The third edition, which bears the name of both Lamarck and de Candolle, was in reality the work of the latter, the former having only lent his name and access to his collection. In 1804, de Candolle published his
Essai sur les propriétés médicales des plantes and was granted a doctor of medicine degree by the medical faculty of Paris. Two years later, he published
Synopsis plantarum in flora Gallica descriptarum. de Candolle then spent the next six summers making a botanical and agricultural survey of France at the request of the French government, which was published in 1813. In 1807, he was appointed professor of botany in the medical faculty of the
University of Montpellier, where he would later become the first chair of botany in 1810. His teaching at the University of Montpellier consisted of field classes attended by 200–300 students, starting at 5:00 am and finishing at 7:00 pm. During this period, de Candolle became a close acquaintance of the Portuguese
polymath,
José Correia da Serra, who was Portuguese ambassador to Paris and who circulated in an international network of thinkers ranging from the Briton
Joseph Banks to the Americans
Thomas Jefferson and
William Bartram, and the French scholars
Antoine Laurent de Jussieu and
Georges Cuvier. Correia's endorsement of the idea of emphasizing similarity and symmetry in classifying plants influenced de Candolle, who acknowledged as much in his writing. While in
Montpellier, de Candolle published his
Théorie élémentaire de la botanique (Elementary Theory of Botany, 1813), which introduced a new classification system and the word
taxonomy. Candolle moved back to Geneva in 1816 and in the following year was invited by the government of the Canton of Geneva to fill the newly created chair of natural history. De Candolle spent the rest of his life in an attempt to elaborate and complete his natural system of botanical classification. de Candolle published initial work in his
Regni vegetabillis systema naturale, but after two volumes he realized he could not complete the project on such a large scale. Consequently, he began his less extensive
Prodromus Systematis Naturalis Regni Vegetabilis in 1824. However, he was able to finish only seven volumes, or two-thirds of the whole. Even so, he was able to characterize over one hundred families of plants, helping to lay the empirical basis of general botany. Although de Candolle's main focus was botany, throughout his career he also dabbled in fields related to botany, such as
phytogeography,
agronomy,
paleontology, medical botany, and
economic botany. In 1827, he was elected an associated member of the
Royal Institute of the Netherlands. ==Later life==