In this lecture Arrighi gave in 1939, he provides a very thorough analysis of the idea of "semi-periphery". He questions the frequently quoted connection by which the level of development would be equivalent with the level of industrialisation. He interprets the latest stage of industrialisation as the shift of industry to the periphery and not as a peripheral development. He challenges the idea that unequal exchange would be the main basis of the economic power of the centre. In this process, the placement of capital and labour is more decisive. He puts forward the theory that this economy is based on the double nature of exploitation and exclusion and if a peripheral country fights against one of the two, then it is to lead to the trap of the other in most cases. Catching up is an illusion for the majority because the advantages they want to reach originate from the very fact that others are subordinated to exclusion and exploitation. Analysing the most different regions of the world, he states that on the scale of periphery-semi-periphery-periphery the up or down movement is exceptional. He opposes the anti-system and pro-system semi-periphery which despite the failure of the "anti-system" socialism is mostly more disadvantageous for the pro-system semi-periphery.