The species and the genus are always the work of nature [i.e. specially created]; the variety mostly that of circumstance; the class and the order are the work of nature and art.
Philosophia Botanica (1751), aphorism 162. Trans. Frans A. Stafleu, Linnaeus and the Linnaeans: The Spreading of their Ideas in Systematic Botany, 1735–1789 (1971)