Unlike the mechanical physicians, the chemists explain the beneficial operation of iron by supposing that it increases the proportion of red globules in the blood, on the erroneous[[42]] hypothesis that iron constitutes the principal element of these bodies. Thus has iron, from its acknowledged powers, been enlisted into the service of every prevailing hypothesis; and it is not a little singular, as a late writer has justly observed, that theories however different, and even adverse, do nevertheless often coincide in matters of practice, as well with each other as with long established empirical usages, each bending as it were, and conforming, in order to do homage to truth and experience. And yet iron, whose medicinal virtues have been so generally allowed, has not escaped those vicissitudes in reputation which almost every valuable remedy has been doomed to suffer: at one period the ancients imagined that wounds inflicted by iron instruments, were never disposed to heal, for which reason Porsenna, after the expulsion of the Tarquins, actually stipulated with the Romans that they should not use iron, except in agriculture; and Avicenna was so alarmed at the idea of its internal use as a remedy, when given in substance, that he seriously advised the exhibition of a magnet[[43]] after it to prevent any direful consequences. The fame even of Peruvian bark has been occasionally obscured by the clouds of false theory some condemned its use altogether, “because it did not evacuate the morbific matter,” others, “because it bred obstructions in the viscera,” others again, “because it only bound up the spirits, and stopped the paroxysms for a time, and favoured the translation of the peccant matter into the more noble parts.” Thus we learn from Morton,[[44]] that Oliver Cromwell fell a victim to an intermittent fever, because the Physicians were too timid to make a trial of the bark. It was sold first by the Jesuits for its weight in silver;[[45]] and Condamine relates that in 1690, about thirty years afterwards, several thousand pounds of it lay at Piura and Payta for want of a purchaser.
Nor has Sugar escaped the venom of fanciful hypothesis. Dr. Willis raised a popular outcry against its domestic use, declaring that “it contained within its particles a secret acid—a dangerous sharpness,—which caused scurvys, consumptions, and other dreadful diseases.”[[46]]
Although I profess to offer merely a few illustrations of those doctrines, whose perverted applications have influenced the history of the Materia Medica, I cannot pass over in silence that of John Brown, “the child of genius and misfortune.” As he generalized diseases, and brought all within the compass of two grand classes, those of increased and diminished excitement, so did he abridge our remedies, maintaining, that every agent which could operate on the human body was a Stimulant, having an identity of action, and differing only in the degree of its force; so that, according to his views, the lancet and the brandy bottle were but the opposite extremes of one and the same class: the mischievous tendency of such a doctrine is too obvious to require a comment.
But the most absurd and preposterous hypothesis that has disgraced the annals of medicine, and bestowed medicinal reputation upon substances of no intrinsic worth, is that of the Doctrine of Signatures, as it has been called, which is no less than a belief that every natural substance which possesses any medicinal virtue, indicates by an obvious and well-marked external character, the disease for which it is a remedy, or the object for which it should be employed![[47]] This extraordinary monster of the fancy has been principally adopted and cherished by Paracelsus, Baptista Porta, and Crollius, although traces of its existence may be certainly discovered in very ancient authors. The root of the Mandrake, from its supposed resemblance to the human form, was esteemed as a remedy for Sterility: thus did Rachael demand from her sister the Mandrakes (Dudaim) which Reuben had gathered in the field; impressed, as it would appear, with a belief in the efficacy of that plant against barrenness.[[48]] There would moreover appear in this case to have been some idea of additional virtue arising from the person who gathered it, for great stress was laid upon this circumstance, “my son’s Mandrakes:” such a notion is by no means uncommon in the history of charms. The supposed virtues of the Lapis Ætites, or Eagle stone,[[49]] described by Dioscorides, Ætius and Pliny, who assert that if tied to the arm it will prevent abortion, and if fixed to the thigh forward delivery, were, as we learn from ancient authority, solely suggested by the manner in which the nodule contained within the stone moves and rattles, whenever it is shaken. “Ætites lapis agitatus, sonitum edit, velut ex altero lapide prægnans.” The conceit however did not assume the importance of a theory until the end of the fourteenth century, at which period we find several authors engaged in the support of its truth, and it will not be unamusing to offer a specimen of their sophistry; they affirm, that since man is the lord of the creation, all other creatures are designed for his use, and therefore, that their beneficial qualities and excellencies must be expressed by such characters as can be seen and understood by every one; and as man discovers his reason by speech, and brutes their sensations by various sounds, motions, and gestures, so the vast variety and diversity of figures, colours, and consistencies, observable in inanimate creatures, is certainly designed for some wise purpose. It must be, in order to manifest these peculiar qualities and excellencies, which could not be so effectually done in any other way, not even by speech, since no language is universal. Thus, the lungs of a fox must be a specific for asthma, because that animal is remarkable for its strong powers of respiration. Turmerick has a brilliant yellow colour, which indicates that it has the power of curing the jaundice; by the same rule, Poppies must relieve diseases of the head; Agaricus those of the bladder; Cassia fistula the affections of the intestines, and Aristolochia the disorders of the uterus: the polished surface and stony hardness which so eminently characterise the seeds of the Lithospermum Officinale (Common Gromwell) were deemed a certain indication of their efficacy in calculous and gravelly disorders; for a similar reason the roots of the Saxifraga Granulata (White Saxifrage) gained reputation in the cure of the same disease; and the Euphrasia (Eye-bright) acquired fame, as an application in complaints of the eye, because it exhibits a black spot in its corolla resembling the pupil.
In the curious work of Chrysostom Magnenus, we meet with a whimsical account of the Signature of Tobacco. “In the first place,” says he, “the manner in which the flowers adhere to the head of the plant indicates the Infundibulum Cerebri, and Pituitary Gland. In the next place, the three membranes of which its leaves are composed announce their value to the stomach which has three membranes.”[[50]]
The blood-stone, the Heliotropium of the ancients, from the occasional small specks or points of a blood red colour exhibited on its green surface, is even at this day employed in many parts of England and Scotland, to stop a bleeding from the nose; and nettle-tea continues a popular remedy for the cure of Urticaria. It is also asserted that some substances bear the Signatures of the humours, as the petals of the red rose that of the blood, and the roots of rhubarb and the flowers of saffron, that of the bile.[[51]]
I apprehend that John of Gaddesden, in the fourteenth century, celebrated by Chaucer, must have been directed by some remote analogy of this kind, when he ordered the son of Edward the First, who was dangerously ill with the small-pox, to be wrapped in scarlet cloth, as well as all those who attended upon him, or came into his presence, and even the bed and room in which he was laid were covered with the same drapery; and so completely did it answer, say the credulous historians of that day, that the Prince was cured without having so much as a single mark left upon him.
In enumerating the conceits of Physic, as relating to the Materia Medica, we must not pass over the idea, so prevalent at one period, that all poisonous substances possess a powerful and mutual elective attraction for each other; and that consequently, if a substance of this kind were suspended around the neck, it would, by intercepting and absorbing every noxious particle, preserve the body from the virulence of contagious matter. Angelus Sala, accordingly, gives us a formula for what he terms his Magnes Arsenicalis, which he asserts will not only defend the body from the influence of poison, but will, from its powers of attraction, draw out the venom from an infected person. In the celebrated plague of London, we are informed that amulets of arsenic were upon this principle suspended over the region of the heart, as a preservative against infection.
There is yet to be mentioned another absurd conceit which long existed respecting the subject of Antidotes,—a belief that every natural poison carried within itself its own antidote; thus we learn from the writings of Dioscorides, Galen, and Pliny, that the virus of the Cantharis Vesicatoria existed in the body of the fly, and that the head, feet, and wings, contained its antidote; for the same potent reason were the hairs of the rabid dog esteemed the true specific for Hydrophobia.[[52]]