6 
of profits to total incomes is a multipier which determines the 
increase in incomes consequent on an increase in investment 
plus capitalist consumption. The explicit treatment of the role 
of distribution in the generation of effective demand is the 
most important distinctive feature of Kalecki's system. There 
are others such as the explicit treatment of the lag between 
investment decisions and investment, and the use_made of the 
argument that investment is pre-determined by decisions made in 
the past. Finally, there is a trade cycle theory, where in 
Keynes there is none. 
The cycle theory was presented by Kalecki at the Econometric 
Society meeting in Leyden in 1933. He came to know Ragnar 
Frisch from whom he took over a decisive improvement of his 
trade cycle theory (the random shocks.) . 
It is remarkable that the aim to explain the trade cycle was 
for Kalecki the pretext to re-write economic theory in terms 
of macro variables, effective demand, and process analysis. 
His analysis is scientific in spirit, his way of thinking is 
mathematical, with a sparing use of the tools of mathematics. 
"He does it just as a scientist would" was the comment of a 
physicist on reading his book of 1939. This is in glaring 
contrast to the formalistic and ornamental use of mathematics 
in much of present day economics ("playometrics" said R.Frisch