to describe the inorganic earth
dynamically in terms of natural law, using chemistry, physics,
mathematics, and even botany and zoology so far as they relate to
paleontology. But he does not insist that the relative importance of
physical or chemical factors shall be determined before he applies the
methods and data of these sciences to his problem. Indeed, he has
learned that a geological area is too complex a thing to be reduced to a
single explanation. He has abandoned the single hypothesis for the
multiple hypothesis. He creates a whole family of possible explanations
of a given problem and thus avoids the warping influence of partiality
for a simple theory.

Have we not here an illustration of what is possible and necessary for
the historian? Is it not well, before attempting to decide whether
history requires an economic interpretation, or a psychological, or any
other ultimate interpretation, to recognize that the factors in human
society are varied and complex; that the political historian handling
his subject in isolation is certain to miss fundamental facts and
relations in his treatment of a given age or nation; that the economic
historian is exposed to the same danger; and so of all of the other
special historians?

Those who insist that history is simply the effort to tell the thing
exactly as it was, to state the facts, are confronted with the
difficulty that the fact which they would represent is not planted on
the solid ground of fixed conditions; it is in the midst and is itself a
part of the changing currents, the complex and interacting influences of
the time, deriving its significance as a fact from its relations to the
deeper-seated movements of the age, movements so gradual that often only
the passing years can reveal the truth about the fact and its right to a
place on the historian's page.

The economic historian is in danger of making his analysis and his
statement of a law on the basis of present conditions and then passing
to history for justificatory appendixes to his conclusions. An American
economist of high rank has recently expressed his conception of "the
full relation of economic theory, statistics, and history" in these
words:

A principle is formulated by _a priori_ reasoning concerning
facts of common experience; it is then tested by statistics
and promoted to the rank of a known and acknowledged truth;
illustrations of its action are then found in narrative