Guettard, famously blunt, was a pioneer of geological field-work. He studied botany with Réaumur and Jussieu. Linnaeus corresponded, naming a genus after him; Haller and the amateur botanist Rousseau were also in contact. Lavoisier’s father was a friend of Guettard, who employed the young Lavoisier as an assistant (encouraging him to go on to study chemistry); they made several geological field-trips together, and were commissioned to produce the first (unfinished) geological map of France. Daubenton was a close colleague. Buffon approvingly quoted Guettard’s Polish researches, despite the animosity between them.