Hoover thought like a geologist all his life. One can see it at the beginning of his memoirs, where he mentions the railroad that ran through his boyhood hometown in Iowa and then lists the rocks that made up the gravel in the roadbed. [Louis] Janin and others saw it in his remarkable ability to read the geology of a landscape— he could survey a mine, Janin said, more quickly than anyone who had ever worked for him. The fascination of what was difficult at Stanford had worked profound changes on this unpromising youth from the provinces and transformed him into a purposeful, successful man.
—Hendrik Booraem V
What is most noteworthy about the man who turned forty just as World War I broke out is not how far short he fell from Olympian standards or even how high he had risen from humble and unpromising beginnings. Rather, it is how broad and deep a human being he had become and how much he had gotten out of his adventurous early manhood. It is not too much to say that Herbert Hoover personified the best that America could offer to the world as the twentieth century took its true and tragic shape in the years after 1914.
—John Milton Cooper, Jr.