Signatura Rerum Theory
Natural things sometimes resemble each other. From antiquity to today, either in the East or the West, such similarity is often considered to be a hidden key toward important knowledge for human beings. To recognize this similarity needs a sort of index, which measures resemblance between things. A general index can be the external figure of natural things. This is the foundation of the theory called “signature/sign of things” (signatura rerum). According to a typical understanding of the sixteenth century, the invisible internal essence or force of natural things was visibly coined on their external figure as a sign. Human beings could decipher such signs by analogy and approach to the universal knowledge of nature or even to the will of God who engraved these signs in nature. The doctrine of signatura rerum was a manifestation of this way of reasoning and approach to nature. French philosopher Michel Foucault (1926–1984) addressed it in Les mots et les choses (The Order of Things), Chapter 2, and made it well known (Foucault. Les mots et les choses: Une archéologie des sciences humaines. Gallimard, Paris, 1966).
KeywordsAnalogical Reasoning Bodily Organ Natural Thing External Figure Wild Olive
Historically speaking, this kind of analogical reasoning can be observed everywhere in the world, especially in the field of medicine. A plant, whose figure resembles hands, was often considered to be efficient for the diseases of hands. If the external appearance of some plants (or sometimes even animals and minerals) resembles the organs of the human body, those plants were believed to be efficient to the diseases and injuries of the corresponding organs.
In Europe, a portion of this doctrine can be observed in the Materia medica of Dioscorides, who synthetized the knowledge of pharmacological botany in the ancient Greek world, and in the Natural History of Pliny of Rome. Their Western followers of the Middle Ages widely used to acknowledge morphological analogies between medicinal natural things and sick or wound parts of bodily organs. Externally resembling plants were applied for the remedy of the bites by beasts such as snakes and scorpions. Thus, the morphological analogy among natural things was often used in medicine.
In the Renaissance, the doctrine of signatura rerum became popular and was discussed widely more than ever. Two major actors contributed to this move: Giambattista Della Porta (1538–1615) and Paracelsus (1493/1494–1538).
Della Porta devoted an entire monograph, entitled Phytognomonica (Naples, 1588), to this doctrine. In this work, he enumerated medicinal plants by way of the morphological analogy with the bodily organs. Citrus fruits, by their resemblance with the heart, were considered to be efficient to cardiac diseases. A plant called “pulmonaria” would be efficient for the sicknesses of the lungs. Corydalis was regarded as a medicine of the liver by its external resemblance to the organ. As pomegranates and toothworts resembled the teeth, they were taught to be good for the pains of the teeth. Likewise, he enumerated medicines for the hand, bones, hairs, head, eyes, ears, genital organs, spleen, kidneys, uterus, bladder, etc. (Della Porta 1588).
Not only the shapes of plants but also colors, smells, and other properties were taken into account. Long-life plants were believed to be good for longevity; plants having yellow flowers or saps would cure jaundice; the red petals of roses would purify the blood by purging heat. More curiously, animals having big ears were said to be efficient to bad hearing capacity; plants growing on the rocks would break calculus; summer plants would be good for summer diseases. Animals, which slept well, would be good for the problem of sleep (Thorndike 1923–1958). By compiling the sum of knowledge about various plants and their signs, Della Porta claimed to follow the tradition which ran from antiquity through the Middle Ages (Della Porta 1588). For him, to understand the correspondence between the human being and medicinal natural things was to reveal the secret of nature, which was also the ultimate goal of his masterpiece, Magia naturalis (Naples, 1589).
As for Paracelsus, he tried to approach this doctrine in a more practical aspect. As a medical practitioner, he dealt with plants as medicines according to the analogy with the bodily organs. He believed that each disease had its own remedy which lay hidden as an invisible faculty or power in plants. For him, physicians had to extract this faculty and learn which plant had which faculty. The privileged way to seek such faculties of plants was an analogical thinking, and the signs of things held the key to such knowledge. For example, as Eufrasia resembled the eye, Paracelsus considered it to be efficient for eye diseases; he regarded melissa to be good for cardiac diseases since it resembled the heart to his eyes. In the case of johanniskraut, he emphasized the importance of deciphering the veins and fine holes of its leaves as well as the whole shape of its leaves and flowers. For him, the external figures of diverse plants and the particular shapes of their parts were the signs to discover and justify medicines (Paracelsus 1922–1933).
Paracelsus extended his theory from the kingdom of plants to the whole field of nature. He went even further to relate it with celestial bodies on the basis of the correspondence between macrocosm and microcosm. As he was not satisfied with the application of this doctrine to medicine alone, he elaborated it to the level of an overall natural philosophy. By this system, he wanted to find out the useful knowledge for human beings and to understand the truth of the world through the study of nature (Müller-Jahncke 1984, 1985; Bianchi 1987; Bono 1995). Later in his career, Paracelsus tried to transform his theory into a tool to craft a better society. For him, if shoemakers do a better job by learning the signs of leather, carpenters by those of wood, potters by those of clay, the life of those who use their products would be made better. Each profession would contribute to society as a whole by gaining its professional knowledge through a better understanding of the signs of things. In this scheme, Paracelsus’s doctrine of signatures was a practical technique as well as practical philosophy (Paracelsus 1922–1933).
Thanks to Paracelsus’s followers such as Joseph Du Chesne (1544–1609), Oswald Croll (1580–1609), Jacob Böhme (1574–1624), Jacques Gaffarel (1601–1681), and Wolfgang Fabricius (1625–1653), the doctrine of signatura rerum knew the vague in the seventeenth century (Du Chesne 1603; Croll 1609; Böhme 1621; Fabricius 1653; Hirai 2014). Its afterlife continued in the eighteenth and nineteenth centuries. In this connection, it is possible to say that Kepler (1571–1630) and Leibniz (1646–1716) were under the influence of Paracelsus (Bianchi 1987). Although historian of botany Agnes Arber (1879–1960) criticized it as an obstacle for the development of modern botanical science, the doctrine served as the intellectual foundation of natural philosophy more strongly in that era than in antiquity and the Middle Ages (Arber 1919).
This kind of reasoning based on analogies had a problem. If the thorough knowledge about the world was sought by analogy through such signs, the world and its knowledge would share the essentially same structure and become a complex tapestry of interwoven analogies. This correspondence did not signify the identity of the world and its knowledge. Even if similarity between plants and human organs was acknowledged, these plants could not cure the sickness of the corresponding organs.
However, such a gap between the world and its knowledge did not lead to the total rejection of analogical reasoning. The divergence between both demanded another analogy to justify the first analogy. As plants similar to the heart were not only citrus but also melissa or lemon, one analogy required another analogy. By this, the network of analogies in the world became stronger. At the same time, the gap covering nature with a veil of mystery sometimes brought forth an unexpected cognition. In his Natural Magic, Della Porta described mysterious connections of natural things: pigeons would use the leaves of laurel to protect their babies against magic; elephants would use wild olives as antidotes when they ate chameleons by error.
Since signs were regarded as the words inscribed onto nature by God, they bore the absolute certificate of trueness. Thus, the truth had to be sought by tracing the endless chain of these signs (Bianchi 1987; Bono 1995). As everything in the world was believed to be connected by analogy and full of signs to decipher, the world itself was “magical.” Paracelsus emphasized the necessity to experience the natural world endowed with this endless chain of signs. What he called “experience” was the very “magic” (magia), which aimed to reveal the concealed relationship among natural things. The doctrine of signatura rerum necessarily comprised magic and experience, both of which were very important in the Renaissance (Kikuchihara 2013).
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