Carolus Linnaeus was a botanist, physician, teacher, writer, and administrator. He was the most influential naturalist of his time and the founder of biological taxonomy. His eminence is due to the development of biological classification systems for plants and animals. Born in Rashult, Sweden, Linnaeus, also known as Carl von Linne, studied at the universities of Lund and Uppsala and at Harderwyck, where he received a degree in medicine. At the age of 25, Linnaeus undertook an expedition to Lapland to collect exotic plants. This expedition marked the beginning of a project that would involve him for 20 years in naming, describing, and classifying every organism known to the Western world. While pursuing his botanical and taxonomic research, Linnaeus practiced medicine to earn a living. As his research progressed, he published numerous works, including 12 editions of "Systema Naturae" (1735), "Species Plantarum" (1753), "Philosophia Botanica" (1751), and "Genera Plantarum" (1737). In 1741, he was appointed to a chair at Uppsala, and in the following year he accepted a chair in botany at the same institution. By 1758, Linnaeus had completed his taxonomic project by classifying 4,400 species of animals and 7,700 species of plants. In middle age, he became a university administrator. In 1770 Linnaeus became ill and remained sick until his death. Linnaeus's enduring contributions were the development of the principles and methods for defining taxonomic groups and the establishment of uniform taxonomic systems. His systems are still used with some modifications and revisions.