lay specific variations in specific
human capacities. There is, save abstractly, no such thing as
a standard human being. We may intellectually set up a
norm or standard, but it will be a norm or standard from
which every individual is bound to vary.

The fact that individuals do differ, and in specific and definable
respects, has most serious consequences for social life.
It means, briefly, that while general inferences may be drawn
from wide and accurate observations of the workings of human
nature, these inferences remain general and tentative,
and if taken as rigid rules are sure to be misleading. Theories
of education and social reform certainly gain from the general
laws that can be formulated about original human traits,
fatigue, memory, learning capacity, and the like. But they
must, if they are to be applicable, take account also, in a
precise and systematic way, of the variety of men's interests and
capacities. To this fact of variety in the original nature of
different men social institutions and educational methods
must be adapted. Arbitrary rules that apply to human nature
in general do not apply to the specific cases and specific
types of talent and desires. Educational and social organizations
can mould these, but the result of these environmental
influences will vary with individual differences in original
capacities. We can waste an enormous amount of time and
energy trying to train a person without mechanical or mathematical
gifts to be an engineer. We not only save energy and
time, but promote happiness, if we can train individuals so
that their specific gifts will be capitalized at one hundred per
cent. They will be at once more useful to society and more
content with themselves, when they are using to the full their
own capacities. They will at once be unproductive and unhappy
when they find themselves in activities or social situations
where their genuine talents are given no opportunity
and where their defects put them at a conspicuous handicap.

Individuals differ, it must further be noted, not only in
specific traits, but in that complex of traits which is commonly
called "intelligence." In the broadest terms, we mean by an
individual's intelligence his competence and facility in dealing
with his environment, physical, social, and intellectual. This
competence and facility, in so far as it is a native endowment,
consists of a number of traits present in a more or less high
degree, traits,