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Paul of Taranto was a 13th-century Franciscan
alchemist Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in China, India, the Muslim world ...
and author from southern Italy. ( Taranto is a city in Apulia.) Perhaps the best known of his works is his ''Theorica et practica'', which defends alchemical principles by describing the theoretical and practical reasoning behind it. It has also been argued that Paul is the author of the much more widely known alchemical text ''Summa perfectionis'', generally attributed to the spurious Jabir, or
Pseudo-Geber Pseudo-Geber (or "Latin pseudo-Geber") is the presumed author or group of authors responsible for a corpus of pseudepigraphic alchemical writings dating to the late 13th and early 14th centuries. These writings were falsely attributed to Jabir ...
.


Definitions and Concepts

When examining Paul’s work, it is important to make the distinction from modern definitions of words to the definitions used by medieval philosophers and scientists. Substance – Paul does not use “substance” as the modern definition of “material” or “
matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic parti ...
.” Instead, substance describes something that is primary and can exist on its own. Accident – Paul doesn’t use this term as an unexpected/unplanned event. Instead, it is simply an attribute, or adjective, and cannot exist on its own. Form/Substantial Form – Form is something that acts on matter that gives it characteristics (e.g.
color Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associa ...
,
hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
, and heaviness). Substantial form is a fundamental type of “form.” As an example to demonstrate: Substance is simply the object itself, including characteristics that define the object, whereas accidents simply qualify it, but are not necessary for its existence. For example, a bird could be considered the substance, generally combining characteristics such as feathers, a beak, and the ability to lay eggs. Describing a bird as big/small or timid/aggressive simply adds qualification to the bird, but is not defining characteristics of a bird. These concepts of substance and accident stem from Aristotle’s works.


''Theorica et practica''

Nature and intellect relationship Paul argues that human intellect is superior to
nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are p ...
. Therefore, humans must have the ability to manipulate nature as they see fit. Sculptures and painters, for example, use nature (marble for
statue A statue is a free-standing sculpture in which the realistic, full-length figures of persons or animals are carved or cast in a durable material such as wood, metal or stone. Typical statues are life-sized or close to life-size; a sculpture t ...
, paint etc) to create various forms of art. They take natural materials and manipulate them in such a way (chiseling a statue, combining colors/drawing shapes, patterns, and figures) to create artistic works. They are able to in a controllable manner alter and improve nature. This thought is also reflected in the act of writing. “ e hand does not write by the motion alone of nature, but as ruled by intellect through art.” Artists are able to control nature and use it as a tool or instrument. This concept of intellect over nature is derived from the pseudo-Aristotelian
Liber de Causis The ("Book of Causes") is a philosophical work composed in the 9th century that was once attributed to Aristotle and that became popular in the Middle Ages, first in Arabic and Islamic countries and later in the Latin West. The real authorship r ...
. Two categories of arts Paul then identifies two categories of arts: “Purely artificial” art alters the extrinsic form or “form of art” and “perfective art” alters the “intrinsic” form (or form of nature). Purely artificial art only changes nature superficially, whereas perfective art changes the essence of nature. Paul clarifies this distinction through the use of primary and secondary qualities. The primary qualities are the four Aristotelian qualities, hot, cold, wet, and dry, which reside in the
four elements Classical elements typically refer to earth, water, air, fire, and (later) aether which were proposed to explain the nature and complexity of all matter in terms of simpler substances. Ancient cultures in Greece, Tibet, and India had simila ...
(earth, water, air, and fire). Secondary qualities include white, black, sweet, bitter, hard, soft, sharp, and dull. Perfective art alters the primary qualities, while purely artificial art only results in changes among the secondary qualities; essential changes result from changes in primary qualities, while accidental changes are a result of changes in secondary qualities. A painter and sculpture, then, only practice artificial art since they change shapes and colors of material. Physicians are considered to practice perfective art since they attempt to control the four humors, which by their definition are characterized by the primary qualities. Farmers too, practice perfective art since they work with the transmutation power inherent in seeds. An analogous modern example of extrinsic versus intrinsic changes is the difference between a physical and
chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breakin ...
. In a physical reaction, there is no change in the molecules in the system. Boiling water is a classic example: The system starts with liquid water, and when enough heat has been added to the water, the water boils into the gaseous phase. While there has been a
phase change In chemistry, thermodynamics, and other related fields, a phase transition (or phase change) is the physical process of transition between one state of a medium and another. Commonly the term is used to refer to changes among the basic states of ...
, the water molecule, H2O hasn’t broken apart and is still present at the end of the reaction, so this is analogous to an extrinsic change.
Electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from na ...
of water is a chemical change – electricity is used to break water into hydrogen and oxygen gas. Since the molecules present have been changed, this is a chemical change, similar to an intrinsic change. Sulfur-mercury theory of metals One of the goals of ''Theorica et practica'' is to affirm the validity of the
sulfur-mercury theory of metals Abū Mūsā Jābir ibn Ḥayyān (Arabic: , variously called al-Ṣūfī, al-Azdī, al-Kūfī, or al-Ṭūsī), died 806−816, is the purported author of an enormous number and variety of works in Arabic, often called the Jabirian corpus. The ...
, which basically states that
metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typica ...
s are composed of
sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
and mercury and the different proportions between the two form different types of metals. Observations of the reactivity of metals suggest that metals were in fact composed of sulfur and mercury. When metals were heated, they gave off a sulfurous odor. When mercury came in contact with metals such as
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile m ...
,
silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical co ...
, copper,
tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
, or
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, l ...
, an amalgam resulted. These observations lead to the conclusion that metals were composed of both mercury and sulfur. Paul addresses one of the many arguments against the sulfur-mercury theory: that intermediate substances cannot exist between the pure elements and the “final product.” Therefore, metals cannot be broken down into sulfur and mercury. In ''Theorica et practica'', Paul first presents this argument before declining it in a contra and pro fashion. He first states the argument against the sulfur-mercury theory. Essentially the argument is as follows: In order to make “A” from “B and C”, “B and C” become corrupted as soon as they combine to make “A,” so “B and C” clearly cannot exist within “A.” Paul then rebuttals against this argument in two ways: theoretical examples and scientific experimentations. One example is how a smaller number can exist in a larger number. For example, the quantity “3” resides in the quantity “4”; 4 can be viewed as the combination of 3 and 1. A less abstract example is a live tree and a dead one. The difference between them is simply the essence of life or its vegetative soul. The dead tree still contains the substantial form of the wood, so clearly that form must have been there even when the tree was alive. Paul’s experimental approach is to decompose metals into other materials, then attempt to recombine those materials into the metal again. If the sulfur-mercury theory is correct, you can decompose metals into the four elements, but when attempting to recombine the elements, there is no reason for the elements to recombine into any one particular metal. Paul writes that he successfully recreated the same metal after a process of calcining, dissolving, subliming, and lastly reducing metals. Since he was able to recreate the same metal that he started with, he obviously did not break the metal down into the pure elements, but instead into some intermediate phases.Newman, ''Atoms and Alchemy'', 40-42.


Notes

{{authority control Italian alchemists Italian Franciscans 13th-century alchemists 13th-century Italian writers 13th-century Latin writers