of the other to a greater degree than chance would explain. For
instance, the quick learner is slow in forgetting, imagery in one field
implies power to image in others, a high degree of concentration goes
with superior breadth, efficiency in artistic lines is more often
correlated with superiority in politics or generalship or science than
the reverse, ability to deal with abstract data implies unusual power to
deal with the concrete situation. In fact, as far as exact measures go,
negative correlations between capacities, powers, efficiencies, are
extremely rare, and, when they occur, can be traced to the influence of
some environmental factor.

Individuals differ from each other to a much greater degree than has
been allowed for in our public education. The common school system is
constructed on the theory that children are closely similar in their
abilities, type of mental make-up, and capacities in any given line.
Experimentation shows each one of these presuppositions to be false. So
far as general ability goes, children vary from the genius to the
feeble-minded with all the grades between, even in the same school
class. This gradation is a continuous one--there are no breaks in the
human race. Children cannot be grouped into the very bright, bright,
mediocre, poor, very poor, failures--each group being distinct from any
other. The shading from one to the other of these classes is gradual,
there is no sharp break. Not only is this true, but a child may be
considered very bright along one line and mediocre along another.
Brilliancy or poverty in intellect does not act as a unit and apply to
all lives equally. The high specialization of mental powers makes
unevenness in achievement the common occurrence. Within any school grade
that has been tested, even when the gradings are as close as those
secured by term promotions, it has been found in any subject there are
children who do from two to five times as well as others, and from two
to five times as much as others. Of course this great variation means an
overlapping of grades on each side. In Dr. Bonser's test of 757 children
in reasoning he found that 90 per cent of the 6A pupils were below the
best pupils of 4A grade and that 4 per cent of 6A pupils were below the
mid-pupils of the 4A, and that the best of the 4A pupils made a score
three times as high as the worst pupils of 6A. Not only is this
tremendous difference in ability found among children of the same clas