656

PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA

Ȃ

where A, B, C are constant which stand for the initial conditions,
 namely

A=a,(t-0) X,(t- 6),
B = a,;(t = 6) W,
C=a, (t-0) W.

The economic meaning of (V.13), (V.14) at a given point of
time has been discussed already on the occasion of our shortrun
 analysis of chapter II (sections 5 and 6), and there is no
need for repetition here. But besides the determination of quantities
 and prices at a given point of time, the (V.13), (V.14)
now bring out their movements through time as well.
As can be seen, each physical quantity follows a time-path
of its own in time, expanding at a particular rate (g+7;) which
is the sum of two rates of increase: the rate of growth of population
 and the rate of change of per-capita demand. The first
of these two rates is the same for all goods, but the second is
different from one commodity to another. Therefore, unless
per-capita demand remains constant in time (i.e. unless there
is no technical progress) the whole production structure in physical
 terms is changing as time goes on. This means that, while
growing, the system is continually changing the proportions in
which it produces the various commodities.
The (V.14) show moreover that each relative price is also
changing in time in its own way. With the convention of adopting
 W, the wage rate, as numeraire, each price is decreasing at
a rate resulting from a weighted average of the pace at which
technical progress is going on in the sector to which it refers,
and in the sector which produces capital goods for it. Since
all these rates are also different from one another, the whole
price structure is changing as time goes on

101 Pasinetti - pag. 86