At the beginning of the nineteenth century another model emerged: that of the chemical )peration, which, by isolating the component elements, made it possible to define the composition, to establish common points, resemblances, and differences with other totalities, and thus to Iixind a classification that was no longer based on specific types but on forms of relations: 'Instead of following the example of die botanists, should not the nosologists have, rather, taken as their model the systems of the chemistmineralogists, that is, be content to classify the elements of diseases and their more frequent combinations?'