Father De Smet's methods of writing were those of any careful investigator. The following reference to his study of the Missouri river is a good example of all his work: I spend my leisure hours in reading and taking notes upon the Missouri and its tributaries and upon the immense territory of 500,000 square miles that it drains. I investigate, I draw upon my own fund of information, and then I write." He drew from many sources, particularly the traders at the remote posts with most of whom he was on terms of close friendship. Among those whom we know to have furnished him information which found its way into his letters are Alexander Culbertson and E. T. Denig, distinguished traders of the American Fur Company, Zephyr Rencontre and Charles E. Galpin, interpreters, and Joseph La Barge, pilot. It was his constant habit to pick up information from every source available and jot it down for future use.
We have already referred to the great volume of Father De Smet's literary work. Considering the absence of extraneous mechanical aids which are now regarded as indispensable, as, for example, stenography and typewriting, the actual physical labor involved in his work appears incredible. Many of his longer letters were copied several times in his own hand, showing that in large degree he had to depend upon himself even for the purely mechanical labor of making necessary copies. He wrote a clear hand, and at times reduced it to a degree of fineness which is simply marvelous. The Jesuit training cultivated a fine hand, and the necessity of economy when paper was scarce and postage high accentuated the habit. To cite a single example, one of the letters is so finely written that a single page of ordinary letter size contains 1,231 words whereas a modern hand would fill it with from 150 to 250 words.
Father De Smet kept copies of nearly all his published letters and these are now scattered through several letterbooks without any careful index. He apparently did not begin to keep copies of his personal letters until about