mentary psychology also plays its part. One of the
subdivisions of the Negro race is composed of persons of mixed blood. In
many instances these are more white than black, yet the association of
ideas has through several generations identified them with the
Negro--and in this country friction between this class and white people
is on some lines even greater than between whites and blacks.

Race conflicts are merely the more pronounced concrete expressions of
such friction. They are the visible phenomena of the abstract quality of
racial antipathy--the tangible evidence of the existence of racial
problems. The form of such expressions of antipathy varies with the
nature of the racial contact in each instance. Their different and
widely varying aspects are the confusing and often contradictory
phenomena of race relations. They are dependent upon diverse conditions,
and are no more susceptible of rigid and permanent classification than
are the whims and moods of human nature. It is more than a truism to say
that a condition precedent to race friction or race conflict is contact
between sufficient numbers of two diverse racial groups. There is a
definite and positive difference between contact between individuals and
contact between masses. The association between two isolated individual
members of two races may be wholly different from contact between masses
of the same race groups. The factor of numbers embraces, indeed, the
very crux of the problems arising from contact between different races.

A primary cause of race friction is the vague, rather intangible, but
wholly real, feeling of "pressure" which comes to the white man almost
instinctively in the presence of a mass of people of a different race.
In a certain important sense all racial problems are distinctly problems
of racial distribution. Certainly the definite action of the controlling
race, particularly as expressed in laws, is determined by the factor of
the numerical difference between its population and that of the inferior
group. This fact stands out prominently in the history of our colonial
legislation for the control of Negro slaves. These laws increased in
severity up to a certain point as the slave population increased in
numbers. The same condition is disclosed in the history of the
ante-bellum legislation of the southern, eastern, New England, and
middle western states for the control of the free Negro population. So
today no state in the Union wou