Originally formulated by Scottish economist Adam Smith (1723-1790), vent for surplus is an explanation of why nations export goods, thereby creating international trade.
Domestic economies often are too small to absorb all the output of their markets, thus generating a surplus.
Vent for surplus theory has been developed by Burmese-born British economist HLA MYINT (1920- ) into a study of economic development.
Also see: demographic transition
H Myint, The Economies of the Developing Countries (London, 1963)