Ray John (1627–1705), English naturalist whose work on the structure and habits of plants and animals led to important conclusions on the methodology of classification and gave a strong impetus to the design argument in natural theology. In an early paper he argued that the determining characteristics of a species are those transmitted by seed, since color, scent, size, etc., vary with climate and nutriment. Parallels from the animal kingdom suggested the correct basis for classification would be structural. But we have no knowledge of real essences. Our experience of nature is of a continuum, and for practical purposes kinships are best identified by a plurality of criteria. His mature theory is set out in Dissertatio Brevis (1696) and Methodus Emendata (1703). The Wisdom of God Manifested in the Works of the Creation (1691 and three revisions) was a best-selling compendium of Ray’s own scientific learning and was imitated and quarried by many later exponents of the design argument. Philosophically, he relied on others, from Cicero to Cudworth, and was superseded by Paley. M.A.St.