If these peoples of different ethnic stocks but similar environments manifested similar or related social, economic or historical development, it was reasonable to infer that such similarities were due to environment and not to race.

Thus, by extensive comparison, the race factor in these problems of two unknown quantities was eliminated for certain large classes of social and historical phenomena.
The writer, moreover, has purposely avoided definitions, formulas, and the enunciation of hard-and-fast rules; and has refrained from any effort to delimit the field or define the relation of this new science of anthropo-geography to the older sciences.

It is unwise to put tight clothes on a growing child.

The eventual form and scope of the science, the definition and organization of its material must evolve gradually, after long years and many efforts of many workers in the field.

The eternal flux of Nature runs through anthropo-geography, and warns against precipitate or rigid conclusions.