Jean Louis Rodolphe Agassiz (28 May 1807-14 December 1873), known as Louis Agassiz, was a naturalist, educator, and physician whose literary significance lies in his establishment of a scientific corollary for Emerson's belief that there is a spiritual quality underlying the natural world. Born in French Switzerland, Agassiz was the descendant of a long line of Protestant ministers. Pride in his religious heritage greatly affected Agassiz the scientist, who opposed evolution because of his piety and inculcated romantic idealism into his scientific treatises, claiming that "We may ... come to a full understanding of Nature from the very reason that we have an immortal soul." Agassiz started collecting fishes while he was still attending the gymnasium at Bienne, and at Munich in 1828 he was appointed to classify fishes collected in Brazil. This project resulted in Agassiz's first publication, Brazilian Fishes (Monachii: C. Wolf, 1829-1832). That same year Agassiz received his Doctor of Philosophy degree from Erlangen and in 1830 he earned a degree of Doctor of Medicine, fulfilling a promise to his father. In 1831 he went to Paris where he fell under the influence of Georges Cuvier and Alexander von Humboldt. The latter secured Agassiz a teaching position at Neuchatel, Switzerland, where he began his lifelong research into glaciation, resulting in the delineation of his theory of an "ice age." There he also continued his study of fossil fish (begun in 1829), the findings of which were published in Recherches surles Poissons Fossiles (Neuchatel: Imprimerie de Petitpierre, 1833-1844). Only a few months after Agassiz's arrival in Boston in the fall of 1846, Thoreau was sending him specimens from Concord, and contact with Agassiz apparently resulted in Thoreau's more scientific approach to nature, beginning in the early 1850s. Agassiz also had contact with other literary notables of Boston as one of the founding members of the Saturday Club in 1856, professor of natural history at Harvard College, and founder of his own school which Emerson's daughter, Ellen, attended. Agassiz intended his Contributions to the Natural History of the United States (Boston: Little, Brown, 1857-1862) to be his crowning achievement, but only four of the proposed ten volumes were completed before his death in Cambridge.