SUMMARY AND CONCLUSIONS 251

other methods of research, which may in turn illuminate
or modify the provisional concepts reached by mere
factorization.

So far as it seeks to be strictly scientific, psychology must
beware of supposing that these principles of classification
can forthwith be treated as ' factors in the mind/ e.g. as
* primary abilities ? or as ' mental powers ' or c energies.'
Factors specify not unitary qualities but systematic patterns;
not active entities, but relations between what we loosely
call the mind and what we vaguely call its environment;
i.e. they specify systems of relations between two sets of
relational systems.

These views, I have shown, appear at once more obvious
and more plausible when we consider, not only the more
usual kind of factorial work that begins by correlating traits,
but also the complementary mode of approach that begins
by correlating persons. And the whole interpretation, I
believe, is closely in keeping with the Gestalt-like concep-
tions that the modern physicist offers us when he describes
the material world and that the metaphysician has from
time to time put forward in attempting to describe reality.
On the other hand, the current treatment of factors as
causal abilities implies an antiquated attitude towards both
scientific and metaphysical issues.

As a method of inquiry factor-analysis reveals a close and
suggestive analogy with the mathematical methods em-
ployed in modern physics. It might, therefore, be still
further refined by adopting or adapting some of the newer
instruments of analysis that have been successfully employed
in that sphere. In particular, the use of the theory of
groups might obviate many of the objections commonly
urged against the crudities of mere quantitative calculations
when applied to the mind. Finally, it is argued, instead of
the psychologist invoking postulates and principles appro-
priate only to the simpler sciences, the more complex
sciences might in their turn profitably borrow factorial
methods from psychology.