And ever since we began to incur the condescension of foreigners by trying to be American, we have been conscious of this weak- rootedness in our literature and trying to remedy it. This is why our flood of nature books for a century is so significant. They may seem peculiar instruments for probing tradition--particularly the sentimental ones. The critic has not yet admitted some of the heartiest among them--Audubon's sketches of pioneer life, for example--into literature at all. And yet, unless I am mightily mistaken, they are signs of convalescence as clearly as they are symptoms of our disease. These United States, of course, are infinitely more important than the plot of mother earth upon which they have been erected. The intellectual background that we have inherited from Europe is more significant than the moving spirit of woods and soil and waters here. The graft, in truth, is less valuable than the tree upon which it is grafted. Yet it determines the fruit. So with the books of our nature lovers. They represent a passionate attempt to acclimatize the breed. Thoreau has been one of our most original writers. He and his multitudinous followers, wise and foolish, have helped establish us in our new soil. I may seem to exaggerate the services of a group of writers who, after all, can show but one great name, Thoreau's. I do not think so, for if the heart of the nature lover is sometimes more active than his head, the earth intimacies he gives us are vital to literature in a very practical sense. Thanks to the modern science of geography, we are beginning to understand the profound and powerful influence of physical environment upon men. The geographer can tell you why Charleston was aristocratic, why New York is hurried and nervous, why Chicago is self-confident. He can guess at least why in old communities, like Hardy's Wessex or the North of France, the inhabitants of villages not ten miles apart will differ in temperament and often in temper, hill town varying from lowland village beneath it sometimes more than Kansas City from Minneapolis. He knows that the old elemental forces--wind, water, fire, and earth--still mold men's thoughts and lives a hundred times more than they guess, even when pavements, electric lights, tight roofs, and artificial heat seem to make nature only a name. He knows that the sights and sounds and smells about us, clouds, songs, and wind murmurings, rain-washed earth, and fruit trees blossoming, enter into our sub-consciousness with a power but seldom appraised. Prison life, factory service long continued, a clerk's stool, a housewife's day-long duties--these things stunt and transform the human animal as nothing else, because of all experiences they most restrict, most impoverish the natural environment. And it is the especial function of nature books to make vivid and warm and sympathetic our background of nature. They make conscious our sub-conscious dependence upon earth that bore us.