But if the phthisis haemoptysis complex (despite many distinctions according to individual cases, circumstances, stages) achieves a certain qualitative density in the total series, their connexion will become, over and above any encounter or any gap, outside even the manifest appearance of the phenomena, an essential relation: 'It is by studying the most frequent phenomena and meditating upon the order of their relations and their regular succession that one finds the bases of the general laws of nature'.