Mr. George Darwin contributes to the Contemporary Review of August last a very thoughtful paper on beneficial restrictions to the liberty of marriage. The following extracts which we make will serve to exhibit the author's stand-point, and to stimulate reflection upon a vastly important question which mankind will sooner or later have to face and answer. We do not think it has been proved that insanity has increased out of proportion to the population; but there can be no doubt of the influence of hereditary predisposition in the causation of such insanity as exists.