The Making of Species 
the strong. Similarly the earlier economists con- 
sidered political economy a very simple affair. 
They asserted that men are actuated by but 
one motive—the love of money. All their men 
were economic men, men devoid of all attri- 
butes save an intense love of gold. Experience 
has shown that these premises are not correct. 
Love of family, pride of race, caste prejudices 
are more or less deeply implanted in men, so 
that they are rarely actuated solely by the love 
of money. 
Thus it is that the political economy of to-day 
as set forth by Marshall is far more complex and 
less dogmatic than that of Ricardo or Adam 
Smith. Similarly the political philosophy of 
Sidgwick is very different to that of Herbert 
Spencer. So is it with the theory of organic 
evolution. The theory of natural selection is no 
more able to explain all the varied phenomena 
of nature than is Ricardo’s assumption that all 
men are actuated solely by the love of money 
capable of accounting for the multifarious existing 
economic phenomena. Even as the love of wealth 
is an important motive of human actions, so is 
natural selection an important factor in evolution. 
But even as the majority of human actions are 
the resultant of a variety of motives, so are the 
majority of existing organisms the resultant of 
a complex system of forces. Even as it is the 
duty of the economist to discover the various 
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