The agreement of my observations on the pure effects of medicines with these older ones – although they were recorded without reference to any therapeutic object, – and the very concordance of these accounts with others of the same kind by different authors must easily convince us that medicinal substances act in the morbid changes they produce in the healthy human body according to fixed, eternal laws of nature, and by virtue of these are enabled to produce certain, reliable disease symptoms each according to its own peculiar character.
In those older prescriptions of the often dangerous effects of medicines ingested in excessively large doses we notice certain states that were produced, not at the commencement, but towards the termination of these sad events, and which were of an exactly opposite nature to those that first appeared. These symptoms, the very reverse of the primary action (§ 63) or proper action of the medicines on the vital force are the reaction of the vital force of the organism, its secondary action (§§ 62-67), of which, however, there is seldom or hardly ever the least trace from experiments with moderate doses on healthy bodies, and from small doses none whatever. In the homoeopathic curative operation the living organism reacts from these only so much as is requisite to raise the health again to the normal healthy state (§ 67).
The only exceptions to this are the narcotic medicines. As they, in their primary action, take away sometimes the sensibility and sensation, sometimes the irritability, it frequently happens that in their secondary action, even from moderate experimental doses on healthy bodies, an increased sensibility (and a greater irritability) is observable.
With the exception of these narcotic substances, in experiments with moderate doses of medicine on healthy bodies, we observe only their primary action, i.e., those symptoms wherewith the medicine deranges the health of the human being and develops in him a morbid state of longer or shorter duration.
Among these symptoms, there occur in the case of some medicines not a few which are partially, or under certain conditions, directly opposite to other symptoms that have previously or subsequently appeared, but which are not therefore to be regarded as actual secondary action or the mere reaction of the vital force, but which only represent the alternating state of the various paroxysms of the primary action; they are termed alternating actions.
Some symptoms are produced by the medicines more frequently – that is to say, in many individuals, others more rarely or in few persons, some only in very few healthy bodies.
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.