Excerpt: 'Many persons and many places have claimed the honor of the invention of typographic printing. That these conflicting claims should be made is the most natural thing in the world. Almost all epoch-making inventions and discoveries are of more or less doubtful origin. The reason for this is that such discoveries grow out of conditions and needs. At the time appointed they appear as inevitably as the blossom on the plant. Very likely they appear in several places at once. Often, also like the blossoms on a plant, only one produces what the gardener calls a set, that is, a fruit which ripens and matures seed for reproduction. The state of human knowledge or the pressure of human need may be such that many students are at work at the same time upon problems which seem to demand solution. In this way the theory of evolution, whose adoption, revolutionizing as it did the entire system of human thinking, was the most important event of the nineteenth century, was independently discovered by Darwin and Wallace, who were working at the same time along independent lines of investigation.'