Lecture XVIII

So too must those diseases which can appear as epidemics be studied according to their primary causes. To take an example: in all persons with a disposition to disturbance and damage of the head and breast rhythms, which find their crudest expression in the respiratory rhythm, there is a tendency to be much affected by a certain atmospheric and extra-telluric conditions. Others again, in whom the respiratory system is congenitally sound, are able to resist such influences. Of course we must make allowances for additional influences, and other factors of a complicated kind, but this brief and bare outline may make the principle understood.