nditions and
the issue of the struggle for life. In the same way, the moral,
juridical and political institutions, from effects become causes (there
is, in fact, for modern science no _substantial_ difference between
cause and effect, except that the effect is always the latter of two
related phenomena, and the cause always the former) and react in their
turn, although with less efficacy, on the economic conditions.

An individual who has studied the laws of hygiene may influence
beneficently, for instance, the imperfections of his digestive
apparatus, but always within the very narrow limits of his organic
capacities. A scientific discovery, an electoral law may have an effect
on industry or on the conditions of labor, but always within limits
fixed by the framework of the fundamental economic organization. This is
why moral, juridical and political institutions have a greater influence
on the relations between the various subdivisions of the class
controlling the economic power (capitalists, industrial magnates, landed
proprietors) than on the relations between the
capitalist--property-owners on the one side and the toilers on the
other.

It suffices here for me to have mentioned this Marxian law and I will
refer to the suggestive book of Achille Loria the reader who desires to
see how this law scientifically explains all the phenomena, from the
most trivial to the most imposing, of the social life. This law is truly
the most scientific and the most prolific sociological theory that has
ever been discovered by the genius of man. It furnishes, as I have
already remarked, a scientific, physiological, experiential explanation
of social history in the most magnificent dramas as well as of personal
history in its most trivial episodes--on explanation in perfect harmony
with the entire trend--which has been described as materialistic--of
modern scientific thought.[80]

If we leave out of consideration the two unscientific explanations of
free will and divine providence, we find that two one-sided and
therefore incomplete, although correct and scientific, explanations of
human history have been given. I refer to the _physical determinism_ of
Montesquieu, Buckle and Metschnikoff, and to the _anthropological
determinism_ of the ethnologists who find the explanation of the events
of history in the organic and psychical characteristics of the various
races of men.

Karl Marx sums up, combines and completes these two theorie