The study of the mind was advanced as remarkably during the nineteenth century as any of its sister sciences. Here, as elsewhere, observation grew keener, new instrumental tests were adopted, and interpretation became more sagacious. A fact as commonplace as the length of human babyhood, when it came under the eye of John Fiske, went far to explain the foundations of the family, and how it came about that primitive man, to whom much was given, so added to his gifts that at last the gulf betwixt him and his next of kin became all but infinite. Of the new study of children, which owes a weighty debt to Darwin and Preyer, Professor Sully is a worthy exponent. In the inquiry of Mr. Galton regarding Twins we have a sterling example of the statistical method.