Diathesis

Medical materialism seems indeed a good appellation for the too simple-minded system of thought which we are considering. […] All such mental over-tensions, it says, are, when you come to the bottom of the matter, mere affairs of diathesis (auto-intoxications most probably), due to the perverted action of various glands which physiology will yet discover.

There are, however, distinct differences between diatheses and idiosyncrasies; diatheses definitely tend to the development of disease, for example the scrofulous diathesis of our forebears favours the onset of tuberculosis; idiosyncrasies are abnormal reactions but do not necessarily dispose to disease.

When a coal miner developed the eye disease nystagmus, was this to be diagnosed as due to work conditions or to an inherent constitutional diathesis?