To the latter category belong the so-called idiosyncrasies, by which are meant peculiar corporeal constitutions which, although otherwise healthy, possess a disposition to be brought into a more or less morbid state by certain things which seem to produce no impression and no change in many other individuals.1 But this inability to make an impression on every one is only apparent. For as two things are required for the production of these as well as all other morbid alterations in the health of man – to wit., the inherent power of the influencing substance, and the capability of the vital force that animates the organism to be influenced by it – the obvious derangements of health in the so-called idiosyncrasies cannot be laid to the account of these peculiar constitutions alone, but they must also be ascribed to these things that produce them, in which must lie the power of making the same impressions on all human bodies, yet in such a manner that but a small number of healthy constitutions have a tendency to allow themselves to be brought into such an obvious morbid condition by them. That these agents do actually make this impression on every healthy body is shown by this, that when employed as remedies they render effectual homoeopathic service2 to all sick persons for morbid symptoms similar to those they seem to be only capable of producing in so-called idiosyncratic individuals.
1 Some few persons are apt to faint from the smell of roses and to fall into many other morbid, and sometimes dangerous states from partaking of mussels, crabs or the roe of the barbel, from touching the leaves of some kinds of sumach, etc.
2 Thus the Princess Maria Porphyroghnita restored her brother, the Emperor Alexius, who suffered from faintings, by sprinkling him with rose water in the presence of his aunt Eudoxia (Hist. byz. Alexias, lib. xv, p. 503, ed. Posser); and Horstius (Oper., iii, p.59) saw great benefit from rose vinegar in cases of syncope.