The great events of history are often due to secular changes in the growth of population and other fundamental economic causes, which, escaping by their gradual character the notice of contemporary observers, are attributed to the follies of statesmen or the fanaticism of atheists. John Maynard Keynes
Another cause of change, one less noticeable but fundamental, is the modern growth of population closely connected with scientific and medical discoveries. It is interesting that the United Nations has set up a special Commission to study this question. Emily Greene Balch