26 
POLITICAL ECONOMY 
tiating the experiences relating to it, as I 
have put it. In the case of demand, for 
instance, we do not say, if we are careful 
scientists, that this book, taken as an isolated 
fact, is worth so much to a given person, 
because it cannot be thought of as an isolated 
fact. We merely say that this book makes a 
certain difference to the person in question 
which he values at so much. 
Finally, let it be clearly understood that 
we are not treating of things as they would 
happen in a community of thoroughly selfish 
people who thought only of their own material 
circumstances—in short, we do not now begin 
our economics by postulating the scarecrow 
known as the economic man, as some early 
economists did—unless we are aiming at the 
roughest of approximations. On the con 
trary, we take people as they are, with their 
mixture of meanness and nobility, but in 
studying them from the economic point of 
view we ignore everything, for the time being, 
which, as a cause, is not economic, or, as an 
effect, is not an economic reflex. In brief, 
we abstract not motives and impulses of a 
particular kind, but only activities or aspects 
of activities of a particular kind. So when 
a recent writer exhorted economists “ once 
and for ever to abolish the feverish, over-