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THE I-IYDROLOGIC CYCLE AND THE WISDOM OF GOD A Theme in Geoteleology BY YI-FU TUAN .. ::'. ·:\·~i·\i:J.J ::: ~~ . . . ~~ .: ..... .. " .. The Hydrologic Cycle and the Wisdom of God A THEME IN GEOTELEOLOGY By YI-FU TUAN Published for the University of Toronto Department of Geography by the University of Toronto Press ,f', .\ v' The Hydrologic Cycle and the Wisdom of God A THEME IN GEOTELEOLOGY By YI-FU TUAN Published for the University of Toronto Department of Geography by the University of Toronto Press epeueJ U! pajuPd g961 'ssald OjUOI0.l ,0 Al!SlaA!Un Aq pal(s!Iqnd Al(deliloa9 JO jUaWpedaa OjUOI0.l ,0 Al!SlaA!Un @ Le Prieur: Monsieur, vous regardez sans doute avec un peu de chagrin ces nuages qui s'amassent, & qui nous oteront, selon toutes les apparences, Ie plaisir de la promenade? Le Chevalier: La vue ne mIen paroit plus affligeante depuis que je connois leur destination. C'est pour remplir nos fontaines & nos rivieres que les vapeurs montent de la mer. J'aime voir tous ces gros nuages partir en diligence pour aller porter Ie rafrafchissement & la fertiliM dans les provinces les plus eloignees. C'est tres-reellement une commission dont ils acquittent. Abbe de Pluche, Le Spectacle de la Nature, 1733 a The central concept of the science of hydrology is the socalled hydrologic cycle-the circulation of water from the oceans through the atmosphere to the land, and thence by runoff overland or by infiltration and underground movement back to the sea, or alternatively back to the atmosphere by evapotranspiration. H. E. Thomas and L. B. Leopold, Science, 1964 v PREFACE This work is published in the hope that it will contribute to the conversation of scholars with similar interests. The work must stand on its own merit; a preface that is also a muted apology should not be necessary. However, "the hydrologic cycle and the wisdom of God" is perhaps an unusual theme to be taken up by a geographer. It may therefore be helpful to my geographical readers to know how I have strayed into this channel of research. The present study has two roots: one is my interest in historical attitudes towards dry lands, and the other is a concern for the unity of the several branches of physical geography. We do not have to probe deeply into the history of geographical ideas before we become aware of the very late recognition of the extent of dry lands and of aridity as a climatic fact. There are probably various reasons for this conceptual neglect of a distinctive and fairly accessible environment. One is the dominance in Western thought of the Greek conception of climatic zones; these are astronomically derived and explain temperature rather than precipitation contrasts. In the extensive literature on climatic determinism, for example, we frequently find comparisons of human manners and institutions between cold countries in the north and warm countries in the south; but seldom between wet coasts and dry interiors until the nineteenth century. Another reason for the neglect of the great deserts is, as I hope to show, the dominance in Western thought of the idea of Providence. A provident God will see to it that the finished earth is green with grass and forests; from the Hexameron of St. Basil to the Seasons of James Thomson one encounters evidence of this faith in a green earth. God provides for the earth's fertility by making the oceans so large that they supply sufficient moisture to water the land. He also makes mountains so that surplus water can flow off as rivers to irrigate the land, and in addition bring to it new layers of fertile silt. We have here the major elements of the hydrologic cycle-a concept that has been found to be eminently serviceable in explaining the vii harmonies o