POLITICAL ECONOMY 
40 
12s., I would buy two pounds ; if 9s., four 
pounds ; if 6s., five pounds, and so on. We 
therefore realize that there is one almost 
universal law of demand, namely, that the 
lower the price of a thing which can be bought 
in any quantity, large or small, the more will 
any person buy of it if he buys any at all. 
In framing this law we must be particular 
to bear in mind that demand does not indicate 
just a quantity of the thing demanded, nor 
just a price, but on the contrary, many 
quantities and many prices, and even more, 
namely, the relations between quantities and 
prices. And we must be equally particular 
to remember (if we care about secure founda 
tions) what has been said a few pages back 
concerning utility, and bear in mind that 
demands simply measure the ratios between 
preferences. So I should feel inclined to repeat 
my description of demands as “quantitative 
objective definitions of preferences,” had 
not one or two critics opined that the unsophis 
ticated would be unlikely to understand what 
the statement means. 
At this point the distinction may be drawn 
between private or individual demand on the 
one hand and public, collective, compound or 
market demand on the other hand. The 
latter means the demands of all the people who