The Importance of Being Diligent

Fennec fox pup, 2008
Everland Zoo, South Korea.

In his 1612 landmark book about making glass from raw materials, there is a specific term that Antonio Neri uses repeatedly: "diligence." I count forty-two distinct instances spread throughout the book. Even so, in all of these occurrences, not once does our priest-alchemist uses this term in a casual manner; each appearance is in a critical step, in which he urges his readers to pay extremely close attention to what they are doing. 

If you want to have fine crystal, then in this you must exercise great diligence; when the frit is made with this careful attention, it will be white and pure like snow from heaven.

And

Then you must stir the glass with a paddle, but when the tinsel is calcined well and as directed, it swells so much that it could make all the glass go out of a large crucible. So use diligence in this.

And

All lead precipitating out of the glass must be removed with diligence, throwing it away, so that it does not make the bottom of the crucible break out, as can happen.

One might well ask, why so much attention to diligence? To be sure, there are many important aspects to the successful outcome of a batch of glass. Yet Neri singles out the seemingly simple act of paying attention. One reason is to avoid disasters. The last two quotes above imply that he has seen his share of these.

There is no question that glassmaking is a technically demanding process, where many things can go wrong. But there is more to it than that; Neri’s admonitions may have more to do with developing the proper attitude in a glassmaker. At first, it might seem that a recipe is a recipe is a recipe and as long as one follows it, mental state has no bearing on the situation. Yet as surprising as some may find it, this is definitely not the case. Materials and conditions vary in ways that cannot always be measured. What a recipe specifies is strictly limited by our perceptions and to quote the bard, "There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy."

Unlike some more intellectual pursuits, glassmaking falls into a category of activity in which there is no room for self-indulgence. It does not work to throw the ingredients into a furnace and walk away, assuming that they will react the way we anticipate. They will react, rather, according to the physical laws of nature. Diligence could make the difference between a minor correction and a disaster. For the headstrong, this can be a rude awakening. A would-be glassmaker is forced into a confrontation with stark, unforgiving reality. What one wants or expects has no bearing on the situation, only what one does, and when.

Neri makes clear that this philosophy of diligence is not only required by the novice, but also by the seasoned professional conciatore.

This entire exercise depends on the practice of being a worthy and diligent glass conciatore, because neither sure weight nor measure can be given.

And

The diligent furnace conciatore will meticulously remove any lead that has returned to its metallic state from inside the pot.

And

When working this glass, use the same diligence that the skilled masters use and in so doing you will make material that is perfectly true to the jasper, agate and chalcedony of the orient.

In the early seventeenth century, to be a glassmaker meant becoming a careful observer, ever mindful that Nature does not care a whit about the way you think things should work. 

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)

Conciatore is pleased to reprise the guest-post of independent researcher Maria Grazzini. Maria studied Antonio Neri under the late Professor Paolo Rossi, philosopher and historian of science at the University of Florence. In 2012, Dr. Grazzini published an annotated English translation of Neri's manuscript in the journal Nuncias. [1] In the course of her research, she discovered a plagiarized version of the manuscript, published by 
a famous Jesuit professor in Brescia. His version matches Neri's handwritten manuscript of 1614 word for word.Here is what Maria had to say on the subject:

The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his  in 1670. [2] The entire chapter 20 of his Prodromo is an exact reproduction of Neri's. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted.

Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. His L'Arte Vetraria  was widely read and its reprints and translations appeared over the centuries. [3] Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.
There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini

[1] Grazzini 2012.
[2] Lana Terzi 1670.
[3] Neri 1612, 1613.
* this post first appeared here on 20 November 2013.

Rosichiero Glass

Sunset over Venice

The most famous recipe in Antonio Neri’s book, L'Arte Vetraria, is “#129 Transparent Red.” The reason for its notoriety is, of course, the pure gold used as a pigment. Gold-ruby, or “rubino” is a devilishly difficult color to produce, and was not reliably duplicated until many years after Neri’s death, although pieces made in ancient times have been unearthed.  

Even though gold rubino is Neri's most well known recipe and certainly his most famous red glass, this recipe does not exist in isolation. In fact, it fits in the middle of a group of eleven recipes (120–130) devoted to transparent, or at least translucent red glass, enamel and related preparations. 

120 Transparent Red in Glass.
121 Red Like Blood.
122 Balas Color.
123 To extract the Spirit of Saturn, Which Serves Many Uses in Enamels and Glasses.
124 Rosichiero to Enamel Gold.
125 Rosichiero for Gold by Another Method.
126 How to Fix Sulfur for the Above Described Work.
127 A Glass as Red as Blood, Which Can Serve as Rosichiero.
128 A Proven Way to Make Rosichiero.
129 Transparent Red.
130 The Way to Fix Sulfur for Rosichiero to Enamel Gold.

A particular shade that was popular at the time was known in Italian as "rosichiero." Our glassmaker presents four different recipes and two more on “fixing” sulfur which some of the preparations require. Most dictionaries cite Neri as the first to use of the word 'rosichiero' in print, but we know it was a common term of art among glassmakers much earlier. The French equivalent is "rouge clair." The Spanish edition of L'Arte Vetraria notes that in that language the term is “rosicler,” which is still used today to describe the intense rosy twilight color of a nice sunset.

The red glasses of this group all call for the addition of copper as a colorant and copper has remained a popular pigment up to the present. For instance, red traffic lights that are made of glass are typically tinted with copper. But that is not the entire story; some of Neri's rosichieros also include the addition of sulfur and some require hematite or iron oxide, red lead oxide, manganese oxide, or wine tartar. In his recipe #125 for rosichiero, he starts with four pounds of high quality cristallo glass. To this adds equal parts of tin and lead oxides, mixed together: 

[A]dd this calx little by little, ½ oz at a time, let it incorporate, and watch for when the glass becomes an ash gray color, at which point it will be good. Do not add too much calx because if you overload it, the glass will become white in color, which is not good.When it turns the said gray color, do not add more calx but leave it to clarify. Then have 2 oz fine minium [red lead oxide], add this to the glass, and let it incorporate well, and clarify. When it clarifies well, throw into water, return it to the crucible and leave it for 8 hours [in the furnace]. 

Have ½ oz of calcined copper, that is to say red copper and ½ oz of raw white [wine] tartar. Throw these materials in, and stir them well. Now add a dram of hematite, which the sword makers use for burnishing, and 1 dram of fixed sulfur. Stir and incorporate these powders, and watch. If it is over-colored, give it a little manganese to dilute it. If it is clear of color, add more of the fixed sulfur, hematite, a little red copper and a little white wine tartar at your discretion so it becomes the desired color.

None of these ingredients excepting copper is common in color glass production today; in fact, sulfur is usually considered an undesirable contaminant. Hematite is a naturally occurring mineral form of iron oxide. It is so named because if abraded in water it tints the water red, appearing to bleed. Hematite is not currently used as a red pigment in glass, but it is commonly used in some pottery glazes. 

From a chemistry standpoint, a good guess is that sulfur added to the glass would react with the copper and iron to produce various sulfide compounds. How those compounds affect the color and texture of the glass is an open question. Here is where we get into uncharted territory; four hundred years after Neri’s book was first published, predicting colors based on chemistry is no easier for us than it was for him. The science of color in general remains a difficult nut to crack. However, the fact that there is still much that we do not understand does not prevent us from enjoying the brilliant reds inspired by a good sunset.

* For the technically minded, the University of Oslo has a wonderful presentation on the state of color physics. For the non-technical, take a look – a series of fascinating images that spans the sense of sight and beyond. There is a link address in the "picture credits" for this post.

** This post first appeared here on 24 April 2014.

Don Antonio de' Medici

Don Antonio de' Medici
Frontispiece from Pierfilippo Covoni 1892

In 1612, Priest Antonio Neri published his book of glassmaking recipes. L’Arte Vetraria went on to become a primary reference for glass artisans throughout Europe. He dedicated his book to Prince Don Antonio de' Medici the son of Grand Duke Francesco I:

In all consideration, it is my proud duty to dedicate this book to none other than you, most Illustrious Excellency; for you have always been my outstanding patron. You are a gifted leader in this and in all other noble and worthy developments made continually in all the arts.

As an eleven year-old, Don Antonio was slated to succeed his father as the next Grand Duke of Tuscany, but that situation changed quickly. In the autumn of 1587 the young prince lost both of his parents in the space of a few days. They both fell extremely ill and died within a short time of each other. Rumors flew that they had been poisoned, but forensic investigators have found pernicious malaria pathogens in Francesco’s remains, a disease with symptoms consistent with the reports of physicians on the scene. Historians trace their infection to an outing in the damp forest a few days earlier, where they had probably been bitten by mosquitoes carrying the disease. 

The boy’s uncle, Cardinal Ferdinando took charge, consolidated power and excluded Don Antonio from the royal succession, although he was given a prominent place at court as a diplomat. As part of a deal that he would never marry, he was allowed to keep the title of Prince of Capestrano, to which was added Grand Prior of Pisa, in the Knights of Malta. The deal also gave him possession of the laboratory facility that his father had built and several other properties. That laboratory, the Casino di San Marco would become the prince’s residence and the place where Antonio Neri would learn about glass formulation.

Poor health attended Don Antonio from his first months through the end of his life. Doctors and medical examinations were to become a regular part of his routine; they may well have inspired his later pursuit of medicinal cures, as well as his foray into alchemy, which also involved Antonio Neri. At some point, probably as a teenager, Don Antonio contracted syphilis, a condition that may well have been treated by Antonio Neri’s father who was physician to the royal family.

The prince had played a major part in Neri's life, elevating him into the upper stratum of Florentine craftsmen and to the forefront of alchemical research in Europe. However, in another manuscript, Discorso, we see a different side of Neri. On the subject of turning base metals into gold, the priest was less forthcoming:

I would add that God's providence over human affairs must not easily allow many to acquire this art, particularly not the great princes. It should not be made clear and common to the vulgar, because in this way, gold and silver and consequently coins lose their value, so that the good order of human trade will be disrupted and we should go back to the ancient barter of things that are necessary to a civil life, creating great disruption and confusion.

Although never allowed to marry, over his lifetime Don Antonio managed to have a number of children; his last three sons were ultimately legitimized by the pope as Medici heirs. In the end, it was the slow, progressive ravages of syphilis that brought him down. He died in 1621, at the age of forty-five, unable to leave his bed. He was given a proper funeral, and interred at the Medici chapel of princes in Florence.

*This post first appeared on 12 May 2014.

The Casino di San Marco

The Casino di San Marco, Florence

Antonio Neri wrote the first book entirely devoted to making glass from raw materials. L’Arte Vetraria, or in English, 'The Art of Glassmaking', did not get written in a vacuum. When Neri put pen to paper for his book, he had been making glass for over a decade. He had the opportunity to learn his craft from some of the experts in the field. His first known experience in glassmaking was at the laboratory palace of Don Antonio de’ Medici, a prince from the ruling family of Tuscany. 

The Palace was called the Casino di San Marco. “Casino” not because it was a gambling hall (which it was not) but because this was the name for a palace that was informally organized like a small country house with the living quarters on the ground floor. It was built by Don Antonio’s father, the former Grand Duke, as a place where Nature’s secrets would be discovered and new inventions would be made. Neri worked at the Casino for a couple of years before moving to Pisa and then to Antwerp, all the while making glass. He returned to Florence to publish his book, and thanked Don Antonio for his long patronage. 

Don Antonio's Casino was as much a grand concept as it was a physical space. Completed to his father’s specifications in 1574, it evolved into a prince's palace par excellence. Within its walls, grand dinners were held, productions were staged and poetry was read. In 1605 Michelangelo Buonarroti the younger staged a play there titled "The Christmas of Hercules." In its chambers, music was performed, philosophy debated and diplomacy conducted. In its laboratories, alchemy was nurtured, and glass was formulated. It was a sort of grand royal conservatory, melding together art, letters, drama, music and science. From its courtyard, hunters set forth into the Tuscan hills in search of unicorns, and within its workshops, artisans explored the territory of new materials and natural secrets.

The Royal Foundry, as it was also called, became a place of pride for Grand Duke Ferdinando. It was a place that visiting dignitaries specifically asked to see and tour. Behind the doors of the Casino di San Marco, Antonio Neri and his associates worked their magic. This is probably where he first learned the secrets of Venetian style glass composition and undoubtedly much more. He assisted the prince in his research, formulated herbal remedies and helped in the production of luxury gifts for visiting dignitaries.

This was the way that I made chalcedony in the year 1601, in Florence at the Casino, in the glass furnace there. At that time, the task of scheduling furnace-work fell to the outstanding Mr. Niccolò Landi, my close friend and a man of rare talent in enamel work at the oil lamp. I made many pots of chalcedony in the furnace there. I never deviated from the method stated above, I always prepared the materials well and it always came out beautifully in all my proofs.[1] 

[1] L'Arte Vetraria, Antonio Neri 1612, p. 41.

* This post first appeared here in a shorter form on 12 August 2012.

A Deeper Accomplishment

From Antonio Neri, "Treasure of the World"

MS Ferguson 67, f. 22r.

For the past four centuries, Antonio Neri has been best known as the author of L'Arte Vetraria, the first printed book solely devoted to the art of glass formulation. It is a work committed to the subject of refining raw materials and combining them into a range of glasses, over a rainbow of colors. 'First into print' is a notable distinction, but one that Neri surpasses with ease by a deeper accomplishment. His book provides a rare glimpse of skilled practical knowledge. This was an era when prized techniques were frequently lost to subsequent generations; lost because artisans so often spared the pen. Their precious knowledge went purposely unrecorded, passing in strict confidence from master to apprentice working side by side. Neri preserved the old techniques like no other document has.

That 'first into print' is what we remember him for highlights an age-old problem that dogs historians. It is a simplification that puts a convenient handle on Neri, but at the same time, it de-emphasizes the fact that he was not working alone. It plays into a narrative that history, in general, happens in a parade of discrete jumps due to the brilliant discoveries of individuals working in isolation. This is confirmed by the mythology surrounding Neri – that he was a mysterious lone alchemist, wandering around Europe, evading those who would steal the secret of the philosopher’s stone. A similar narrative is applied to one historical figure after another, a form that is so appealing that it fills many history books of our schoolchildren and dictates the story lines of popular television productions (of a certain ilk) about the history of science and technology.

This is not to deny the limelight to anyone. Neri is a comparatively minor contributor and in my humble opinion definitely deserves recognition and even celebration. The danger is that by reducing history to a list of lone individuals making breakthrough discoveries, we distort the truth of how things are done and more to the point; we miss out on the far richer adventure of what really happens.

Never mind that Neri's book chronicles the work of hundreds or thousands of glassmakers that came before him or that he probably would have been far more grateful to be remembered for his work in alchemy and medicine. What sticks is 'first into print.' The reality is that he had the substantial resources of the Renaissance Medici court at his disposal. There is strong evidence based on his own manuscripts and drawings that he worked among a group of at least a dozen colleagues of both sexes, exchanging ideas, experimenting and urging each other on; a mode that no scientist would deny is far closer to the way discovery and innovation really happen.

This cultural defect in our perception of history is by no means a recent development. Even in Neri's own time, the early seventeenth century, the 'lone man' paradigm was well established. He and his contemporaries thought along similar lines about alchemists Arnold Villanova, Ramon Llull and Paracelsus. Physicians like his father idolized Galen and Dioscorides.

For the first time in history, we each have a tremendous chunk of the past at our fingertips in the form of the internet. It is a golden opportunity, not to be fed history, but to discover it for yourself and perhaps for the rest of us. There is no shortage of connections yet to be made and libraries around the world are availing their treasures freely to anyone with an interest. For a great adventure and an exercise in critical thinking, pick a discovery attributed to your favorite figure in history and ask the question "on whose shoulders was she standing?"

*This post first appeared here on 21 March 2014.

The Neri Chapel

The Vision of St Bernard, by Pietro Perugino (1448–1523)

The c. 1598 altarpiece that was commissioned 

for Cestello by Antonio Neri’s father

On a narrow unassuming street called Borgo Pinti on the northeast side of Florence, there are two structures in particular which are of great interest in the study of seventeenth century glassmaker Antonio Neri. The first is the family’s residence at number 27, now a hotel, but largely intact and the second is the church located a few steps further north, now known as Santa Maria Maddalena dei Pazzi. 

In the sixteenth and early seventeenth century, the church was part of a Cistercian monastery known locally as “Cestello” It was attended by Antonio’s royal physician father Neri Neri, his grandfather, Jacopo and it is safe to assume, the rest of the family. This is where the medical doctor would later be buried. In 1598, he was laid to rest in the chapel that Poccetti and Passignano reworked to his specifications; both were well-respected fine artists of the time. One author would later refer to the space as “the famous Neri chapel.” The royal physician asked, in his will, that his remains never be moved outside of his beloved homeland. He provided money for what amounts to a complete restoration of the entire property. The work in the chapel and the main church was a top to bottom renovation and must have taken several years to complete; today it is considered Poccetti’s crowning achievement. In earlier times, the monks of Cestello had played a trusted role in pre-Medicean Florence, collecting and counting the beans used in votes of the Signoria (town council), and holding the keys to the Palazzo Vecchio.

The chapel and the church still stand, but the occupants changed in 1628-29. Pope Urban VIII was seeking better accommodations for two of his nieces who were Carmelite nuns on the other side of the Arno River at San Frediano Monastery. He asked that the Cistercian brothers, against their protestations, exchange properties with the nuns, who brought with them the remains of Sister Maria Maddalena de’ Pazzi, the influential mystic who died in 1607. The church was renamed in her honor after canonization in 1669. 

The Cistercian’s archives record that:

In 1598 Doctor Neri remodeled in more honorable form the chapel which was originally built by Tommaso del Giglio, in the year 1505, which had since become occupied by the cobblers guild, who had begun to meet there and which he feared they wanted to usurp. Maestro Neri approached the Grand Duke [Ferdinando I] in order to have authority to free it from the hands of the cobblers and enlarge and redo it from the foundation and have it all painted in frescos by the hand of Bernardino Poccetti and dedicated to the honor of Saints Nereus and Achilleus.

Far more than the mere renovation of the chapel, the royal physician played a central role in the rehabilitation of an ancient and venerated church, a church that today continues as a testament to Poccetti’s great talent. Tommaso del Giglio, the former owner of Neri’s chapel and successful apothecary supplied Cestello as well as many Florentine hospitals with medicines and other staples. That the cobblers had occupied the chapel might seem strange. What possible claim could the band of shoe-makers have to this space? The simple answer is that Del Giglio was himself a member of their guild, perhaps the cobbler’s most famous member. About 1462 he moved his family to Florence from Montevarchi, where he was trained as an apothecary. For whatever reason he could not gain membership to the guild in Florence, so instead he joined the subordinate cobblers’ guild but retained his practice as an apothecary. He was still subject to the  rules, regulations and periodic inspections of the authorities. Eventually he attained the honor of apothecary to the ruling Medici family. A century after his death, it seems the chapel and the church itself was falling into disrepair; the cobblers, with the family’s blessing met there on a regular basis.

The Cestello monastery, of which the church was a part, served as an early home to the famed Accademia del Disegno (Florentine Academy of Design). The city’s greatest artists, sculptors and architects were all members, Giambologna not least among them. The rooms of the monastery were used to store artistic works and teach classes. For the members it served as a place to meet and plan projects for the city and royal family. A young Galileo Galilei would study mathematics here under Ostilio Ricci. 

It is unknown if the Neri chapel serves as the last resting place for the children of royal physician Neri Neri, among them his most famous son, glassmaker Antonio Neri, who died in 1614 at the age of thirty-eight.

* This post first appeared here in a considerably shorter form on 28 August 2013.