Laennec, on the other hand, found no difficulty in enveloping the anatomo clinical experience in the space of the nosological division: opening up corpses and finding lesions was to reveal 'the most fixed, most positive, and least variable elements in local diseases'; it was therefore to isolate 'that which must characterize or specify them'; by providing it with more certain criteria, it was, in the last resort, to serve the cause of nosology.