The student of biology is often struck with the feeling that...

The student of biology is often struck with the feeling that historians, when dealing with the rise and fall of nations, do not generally view the phenomena from a sufficiently high biological standpoint. To me, at least, they seem to attach too much importance to individual rulers and soldiers, and to particular wars, policies, religions, and customs; while at the same time they make little attempt to extract the fundamental causes of national success or failure.