SEMAINE D ETUDE SUR LE ROLE DE LANALYSE ECONOMETRIOUE ETC. 
635 
consumers had infinite opportunities of trial and error, they 
must now know their preferences perfectly. The second postul- 
ate thereby reduces to the first). 
This is enough for our purposes. To synthesize these re- 
sults for the following analysis, we may simply state them in 
three propositions: 
a) at each level of per-capita income, the proportion of in- 
come spent on any commodity is generally verv different 
from one commodity to another: 
h) as per-capita real income increases, each increment of de- 
mand tends to concentrate on a particular group of com- 
modities. This group of commodities changes from one level 
of income to another (it may be mainly food at very low 
levels of income, clothes and again food at slightly higher 
levels of income, houses, durables and services of various 
kinds at further higher levels, etc.). In other words, as 
.ncome increases, the tendency of the consumers is not to 
.ncrease proportionally the consumption of already-bought 
commodities, but rather to buy new goods and services or 
also to satisfy old needs with different (better) goods: 
~) 
AW 
there is no commodity for which any individual’s consump- 
tion can be increased indefinitely. An upper saturation level 
exists for all types of goods and services, although at dif- 
ferent levels of income: it may be reached sharply — in the 
case of goods satisfying physiological needs — or only 
through a slow and long process as income increases — in 
the case of services yielding very sophisticated types of 
satisfaction — but its attainment is eventually inevitable. 
Moreover, demand for some particular goods (inferior goods) 
may in fact decrease, after reaching saturation, if real in- 
come persistently goes on growing. 
If we want to represent these results graphically, by plot- 
dng the expenditure for each commodity as a function of real 
10] Pasinetti - pag. 65