“For indeed it is one of the lessons of the history of science that each age steps on the shoulders of the ages which have gone before. The value of each age is not its own, but is in part, in large part, a debt to its forerunners. And this age of ours, if, like its predecessors, it can boast of something of which it is proud, would, could it read the future, doubtless find much also of which it would be ashamed.”