The concept of organic structure already existed in eighteenthcentury natural history just as, in the sphere of the analysis of wealth, the notion of labour was not invented at the end of the Classical age; but it was a concept that served at that time to define a certain mode of composition of complex individuals, on the basis of more elementary materials; Linnaeus, for example, distinguished between 'juxtaposition', which causes growth in minerals, and 'intussusception', which enables the vegetable kingdom to develop by feeding itself.