Every region should retain representative samples of its original or wilderness condition, to serve science as a sample of normality. Just as doctors must study healthy people to understand disease, so must the land sciences study the wilderness to understand disorders of the land-mechanism.

"Planning for Wildlife" [1941]; Published in For the Health of the Land, J. Baird Callicott and Eric T. Freyfogle (eds.), 1999, p. 197.