investigators, scholars, warriors, and so forth, then to divide these
into subclasses, until more appears to be lost through paucity of
material than is gained through its increasing homogeneity.

Whatever group be selected, both ability and environment must be
rated according to the requirements of that group. It then becomes
possible, and it is not difficult, to roughly array individuals under
each of these two heads successively, and to label every person with
letters signifying his place in either class. For purposes of the
following explanation, each quality will be distributed into three
grades, determined not by value, but by class place--namely, the
highest third, the medium third, and the lowest third. In respect to
ability, these classes will be called A, B, and C. In respect to
environment, the grades will refer to its helpfulness towards the
particular success achieved, and the classes will be called E, F, G.
It must be clearly understood that the differences between the grades
do not profess to be equal, merely that A is higher than B, and B
than C; similarly as to E, F, and G. The A, B, C may be quite
independent of E, F, G, or they may be correlated. Both cases will
be considered.

Ability and Environment being mutually helpful towards success, the
successes statistically associated with AE will be reckoned higher
than those associated with AF. Again, for simplicity of explanation
only, it will here be assumed that Ability and Environment are
equally potent in securing success. Any other reasonable relation
between their influences may be substituted for the purpose of
experiment, but the ultimate conclusion will be much the same.

TABLE I.--COMBINATIONS OF ABILITY AND ENVIRONMENT.