history and, on the other hand, the economic law becomes the
interpreter of records that would otherwise be confusing and
comparatively valueless; the law itself derives its final
confirmation from the illustrations of its working which the
records afford; but what is at least of equal importance is
the parallel fact that the law affords the decisive test of
the correctness of those assertions concerning the causes and
the effects of past events which it is second nature to make
and which historians almost invariably do make in connection
with their narrations.[333:1]

There is much in this statement by which the historian may profit, but
he may doubt also whether the past should serve merely as the
"illustration" by which to confirm the law deduced from common
experience by _a priori_ reasoning tested by statistics. In fact the
pathway of history is strewn with the wrecks of the "known and
acknowledged truths" of economic law, due not only to defective analysis
and imperfect statistics, but also to the lack of critical historical
methods, of insufficient historical-mindedness on the part of the
economist, to failure to give due attention to the relativity and
transiency of the conditions from which his laws were deduced.

But the point on which I would lay stress is this. The economist, the
political scientist, the psychologist, the sociologist, the geographer,
the student of literature, of art, of religion--all the allied laborers
in the study of society--have contributions to make to the equipment of
the historian. These contributions are partly of material, partly of
tools, partly of new points of view, new hypotheses, new suggestions of
relations, causes, and emphasis. Each of these special students is in
some danger of bias by his particular point of view, by his exposure to
see simply the thing in which he is primarily interested, and also by
his effort to deduce the universal laws of his separate science. The
historian, on the other hand, is exposed to the danger of dealing with
the complex and interacting social forces of a period or of a country,
from some single point of view to which his special training or interest
inclines him. If the truth is to be made known, the historian must so
far familiarize himself with the work, and equip himself with the
training of his sister-subjects that he can at least avail himself of
their results and in some reasonable d