DEMAND 
51 
things as units of utility the same for me 
as for any other person, the marginal utility 
of a thing for which he and I paid the same 
price would not necessarily be the same for 
both of us since we might differ in respect of 
tastes and intensity, of wants and he might 
be the wealthier. As a person gets wealthier, 
the marginal utility of money to him falls, 
other things being equal. The conclusion 
to which the argument of this paragraph 
meanders is that the surplus in utility enjoyed 
by a group of consumers of a commodity is 
an assemblage of diverse things which cannot 
be added to one another to make up a think 
able whole. 
Consumer’s surplus is more easily compre 
hensible when we think of it in terms of money. 
We may then define it as the difference between 
what a person does give for a thing and what 
he would give rather than be deprived of the 
thing altogether. If I would give £45 for a 
piano upon which I have set my heart, and 
am able to buy it for £20, I enjoy a consumer’s 
surplus of £25 on my acquisition. The £25 
stands for what I have saved in view of the 
fact that I was not compelled to give as much 
for the piano as I was prepared to give. Simi 
larly we may interpret the surplus in the case 
of the apples already treated in terms of utility.