For two millions (some hold even three millions) of years man lived and moved and had his being in a world very different from that upon which we look out.

There appear, indeed, to have been various types of man, some as different from us as we are from the anthropoid apes.

What upstarts of yesterday are the Pharaohs in comparison with the men who survived the tragedy of the glacial period! The ancient history of man--only now beginning to be studied--dates from the Pliocene or Miocene period; the modern history, as we know it, embraces that brief space of time that has elapsed since the earliest Egyptian and Babylonian records were made.

This has to be borne in mind in connection with the present mental status of man, particularly in his outlook upon nature.

In his thoughts and in his attributes, mankind at large is controlled by inherited beliefs and impulses, which countless thousands of years have ingrained like instinct.