evolution that cannot safely be overlooked, and they all vary from age
to age and in place and place.

If it were possible to completely exchange the inhabitants of a large
town in England with those of an equally large town in France two groups
of changes would become more or less rapidly observable: (1) the French
and English citizens would adapt themselves, as far as they desired and
were able, to their altered conditions; (2) the characteristics of both
towns would gradually change, in spite of geographical position, in
response to the altered human needs. Similarly, a town composed of
individuals who are naturally uncultured and unprogressive will tend to
preserve its uncultured and unprogressive characters more than another
that has alert citizens to carry on its activities. Every profession and
every trade tends to foster its own social atmosphere; and towns will
vary with their industrial life, and individuals favourably disposed to
this atmosphere will come to the town, and those unfavourably inclined
to it will leave. _These changing citizens, as they act upon and react
to their surroundings and vary in their powers age by age, are the real
evolvers of the conditions in which they dwell_; hence the citizen must
not be omitted from our study if we are to understand city growth.

In other words, I think that every investigation of civic, and for that
matter country life should be studied from two aspects: (1) to note the
peculiarities, growth and development of the material, non-living and
non-thinking elements in the problem--the buildings, their geographical
position, their age, their fitness for past and present life, and the
distinctive local features that are evolving or retrogressing with the
multiplication of some trades and industries and the decline of others
in each area that is studied; (2) the change in the quality of the
citizens themselves through racial, educational, and other factors,