The old medical theory, which supposed that plants by their external character indicated the particular diseases for which Nature had intended them as remedies, was simply a development of the much older notion of a real connection between object and image. Thus, on this principle, it was asserted that the properties of substances were frequently denoted by their colour; hence, white was regarded as refrigerant, and red as hot. In the same way, for disorders of the blood, burnt purple, pomegranate seeds, mulberries, and other red ingredients were dissolved in the patient's drink; and for liver complaints yellow substances were recommended. But this fanciful and erroneous notion "led to serious errors in practice," [1] and was occasionally productive of the most fatal results. Although, indeed, Pliny spoke of the folly of the magicians in using the catanance (Greek: katanhankae, compulsion) for love-potions, on account of its shrinking "in drying into the shape of the claws of a dead kite," [2] and so holding the patient fast; yet this primitive idea, after the lapse of centuries, was as fully credited as in the early days when it was originally started. Throughout the sixteenth and seventeenth centuries, for instance, it is noticed in most medical works, and in many cases treated with a seriousness characteristic of the backward state of medical science even at a period so comparatively recent. Crollius wrote a work on the subject; and Langham, in his "Garden of Health," published in the year 1578, accepted the doctrine. Coles, in his "Art of Simpling" (1656), thus describes it:—
"Though sin and Satan have plunged mankind into an ocean of infirmities, yet the mercy of God, which is over all His workes, maketh grasse to growe upon the mountains and herbes for the use of men, and hath not only stamped upon them a distinct forme, but also given them particular signatures, whereby a man may read even in legible characters the use of them."
John Ray, in his treatise on "The Wisdom of God in Creation," was among the first to express his disbelief of this idea, and writes:—"As for the signatures of plants, or the notes impressed upon them as notices of their virtues, some lay great stress upon them, accounting them strong arguments to prove that some understanding principle is the highest original of the work of Nature, as indeed they were could it be certainly made to appear that there were such marks designedly set upon them, because all that I find mentioned by authors seem to be rather fancied by men than designed by Nature to signify, or point out, any such virtues, or qualities, as they would make us believe." His views, however, are somewhat contradictory, inasmuch as he goes on to say that, "the noxious and malignant plants do, many of them, discover something of their nature by the sad and melancholick visage of their leaves, flowers, or fruit. And that I may not leave that head wholly untouched, one observation I shall add relating to the virtues of plants, in which I think there is something of truth—that is, that there are of the wise dispensation of Providence such species of plants produced in every country as are made proper and convenient for the meat and medicine of the men and animals that are bred and inhabit therein." Indeed, however much many of the botanists of bygone centuries might try to discredit this popular delusion, they do not seem to have been wholly free from its influence themselves. Some estimate, also, of the prominence which the doctrine of signatures obtained may be gathered from the frequent allusions to it in the literature of the period. Thus, to take one illustration, the euphrasia or eye-bright (Euphrasia officinalis), which was, and is, supposed to be good for the eye, owing to a black pupil-like spot in its corolla, is noticed by Milton, who, it may be remembered, represents the archangel as clearing the vision of our first parents by its means:—
"Then purged with euphrasy and rue
His visual orbs, for he had much to see."
Spenser speaks of it in the same strain:—
"Yet euphrasie may not be left unsung,
That gives dim eyes to wander leagues around."
And Thomson says:—
"If she, whom I implore, Urania, deign
With euphrasy to purge away the mists,
Which, humid, dim the mirror of the mind."
With reference to its use in modern times, Anne Pratt[3] tells us how, "on going into a small shop in Dover, she saw a quantity of the plant suspended from the ceiling, and was informed that it was gathered and dried as being good for weak eyes;" and in many of our rural districts I learn that the same value is still attached to it by the peasantry.
Again, it is interesting to observe how, under a variety of forms, this piece of superstition has prevailed in different parts of the world. By virtue of a similar association of ideas, for instance, the gin-seng [4] was said by the Chinese and North American Indians to possess certain virtues which were deduced from the shape of the root, supposed to resemble the human body [5]—a plant with which may be compared our mandrake. The Romans of old had their rock-breaking plant called "saxifraga" or sassafras; [6] and we know in later times how the granulated roots of our white meadow saxifrage (Saxifraga granulata), resembling small stones, were supposed to indicate its efficacy in the cure of calculous complaints. Hence one of its names, stonebreak. The stony seeds of the gromwell were, also, used in cases of stone—a plant formerly known as lichwale, or, as in a MS. of the fifteenth century, lythewale, stone-switch. [7]