390 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
PASINETTI 
Let me express my thanks, first of all, to Professor MAHALANOBIS 
for his kind words of appreciation. I shall try to answer briefly 
‘he three main questions he has raised. 
The definition of « equilibrium » which I have chosen is not a 
static one. It is a definition, used in macro-dynamic analysis, which 
simply stands for a situation of full employment and full utilization 
of capacity through time. As far as natural resources are concerned, 
for the reasons which I tried to explain, I found that introducing 
them immediately would have put me into those difficulties which 
have kept back for so long marginal analysis from tackling the 
problems of economic growth. I have preferred, therefore, to leave 
them aside, for the time being, although it is my intention to intro- 
duce them later on. Finally, I must say that I am in full agreement 
with Professor MAHALANOBIS on the assertion that simply introducing 
time into a static model does not make it necessarily dynamic. This 
is a point which I have tried to make myself, when for example I 
have criticized the von Neumann-type of growth models, in which 
time is introduced simply in order to bring about an expansion of 
the scale of the system, without altering the structure. In such 
models, the proportions (or structure) of the economic system are 
specified at a given point in time, and then kept constant for ever; 
in other words the structure of the system is independent of time. 
[ have always doubted whether we should call such models dynamic. 
They appear to me only half-dvnamic. 
MAHALANOBIS 
I think I have understood, and I am in complete agreement 
about that very important question of structure, because from the 
point of view of underdeveloped countries, the main objective — at 
least in the initial stages and for a fairly long time — is to change 
the structure of the economy. If I have correctly appreciated the 
10] Pasinetti - pag. 120