Lamarck's chemical theories are usually dismissed as the product of unfortunate speculation because they represented the "old chemistry" overturned by Antoine Laurent Lavoisier and the "chemical revolution." However, they provide the key to his conception of nature and are essential features of his theory of evolution. Lamarck began his work in chemistry in the 1770s, when the four-element theory of matter (earth, air, fire, water) was still generally accepted in France. The fact that the most important element in his system was fire in its various states of modification allowed Lamarck to explain most of the known chemical and physical phenomena. His chemistry was ... used to explain the mechanical interaction of individuals with the environment and, thus, evolution and the emergence of higher mental faculties.