Developmental psychology emerged within the evolutionary, progressive thought of the later part of the 19th century. Concerned with processes by which new forms develop and new phenmena emerge, evolutionary thinking turned readily to the natural history of childhood. In 1877, the great biologist, Charles Darwin, and the philosopher, Hippolyte Taine, published short observations on the early development of their own children. When Wilhelm Preyer, a highly respected physiologiest, followed with his own remarkable and much more extensive observations, the biographical study of childhood had begun in earnest. This series reprints seminal text that defined this movement.