The Cardinal's Ceiling

From Treasure of the World

Antonio Neri 1590-1600

In the years 1598-1600, newly ordained Florentine priest and alchemist Antonio Neri was hard at work on a manuscript which he titled Tesoro del Mondo (Treasure of the World). [1]  One illustration near the front shows an allegorical map in which six roads all lead to the Vatican at its center. A Latin inscription translates as, "The different ways to Rome" followed by "Qui pot[est] capere capiat" or 'He that can take, let him take it.' Taken in context, this Biblical reference ( Matthew 19:12) apparently refers to the various alchemical 'paths' leading to the philosopher's stone, but the choice of imagery suggests that Neri spent time in the city of seven hills. [2] It is a tantalizing clue to his travels, although there is no direct confirmation. 

If Rome did figure in the young Neri's itinerary, a visit to Cardinal Francisco Maria Del Monte would have been de rigueur. The Medici family ruled Neri's home region of Tuscany and Cardinal Del Monte was the Medici's informal ambassador in Rome. He was a dedicated patron of the arts, an amateur alchemist, a collector of glass and a trusted successor to Grand Duke Ferdinando in the College of Cardinals. More significantly, he was a close friend and advisor to Neri's sponsor Don Antonio de' Medici ever since that prince was a child.  Del Monte's biographer Zygmunt Waźbiński offers, "It is very likely that Cardinal Del Monte, with his interest in glass, had known then (in 1598) the [future] author [Neri] of L'Arte Vetraria." [3]

Michelangelo Caravaggio, c. 1597
Casino Ludovisi.

As the sixteenth century ended and a new one dawned, Del Monte sheltered the rough-and-tumble painter Michelangelo Caravaggio, whom he set up with an in-house studio and an allowance. However, in 1606, the master of Realism fled Rome after reportedly murdering a tavern waiter over a tennis wager, but not before executing his only known fresco on the vaulted ceiling of Del Monte's own alchemy laboratory. Looking out over Rome, on the panoramic Pincio, in the Villa that later became the Casino Ludovisi and is now known as the Casino dell'Aurora, Caravaggio put his brush to work. According to early biographer of artists, Gian Pietro Bellori, he executed the oil painting on the vaulted ceiling of the small alchemical laboratory (now a corridor) sometime between 1597 and 1600. [4] Depicted in the mural are the three brothers Jupiter, Neptune and Pluto: the masters of the universe. The image is a double allegory of the three basic chemical substances of Paracelsus (salt sulfur and mercury) and the four Aristotelian elements (air, earth, water and fire). Jupiter with the eagle stands for sulfur and air, Neptune with the seahorse stands for mercury and water and Pluto with the three-headed dog Cerberus stands for salt and earth. Jupiter is reaching out to move the central celestial sphere in which the sun (fire) revolves around the earth. [5] 

The villa was a relatively secluded retreat where the Cardinal could entertain guests discretely, including his friend Galileo–Del Monte and his older brother Guidobaldo helped land Galileo the chair of mathematics at the university in Pisa. It would be interesting to hear the astronomer’s comments on Caravaggio's tribute to heliocentrism.


[1] Neri 1598-1600, f.xxviii-v.  (see bibliography).
[2] For more on the alchemical interpretation of this illustration see Grazzini 2012.
[3] Neri 1612.
[4] Bellori 1672, pp. 197-216.
[5] Wallach 1975, pp. 101-112.

* this post first appeared in a slightly different form on 4 July 2014.

Galleria dei Lavori

Giovanni Stradano  (Jan van der Straet) 

Alchemy Studio, 1571
(Inside the Uffizi Galleria dei Lavori)

In 1560, Cosimo I, Duke of Tuscany, commissioned Georgio Vassari to begin construction on the Uffizi Palace in Florence. Two wings of the structure frame a long, narrow courtyard leading out to banks of the Arno River. Today it houses one of Europe's premier art museums, but its original design was as the central administration of the Medici government. The lower floor held offices of the regional magistrates, and the upper floor of the west wing (above the mint) held a variety of workshops highlighting Tuscan industry. Grand Duke Cosimo de' Medici built a glass furnace there, which he staffed with Muranese masters of the art. He won their expertise through long, hard negotiations with the doge of Venice. 

A 1571 painting by Giovanni Stradano is entitled the Alchemy Studio. It shows Cosmo's son, Francesco I, in the Uffizi surrounded by laboratory equipment and workers. Under the watchful eyes of a senior alchemist, he stirs a chemical preparation over a stove with intense concentration. The prolific glassware in this scene drives home the close relationship between glassmaking and scientific investigation.

By 1588 Francesco's brother, Ferdinando I de' Medici, formally declared this space the Galleria dei Lavori or 'gallery of the works'. There is no direct evidence that Antonio Neri gained his education in alchemy at this facility, but it makes a very attractive candidate. Of note to this story is that a demonstration was performed for Ferdinando de' Medici that purported to turn half of an iron nail into gold; the work of German alchemist Leonhard Thurneysser. In the 1590s, when Neri was being schooled, several accounts describe that the nail (chiodo) remained on display for some time in the Galleria. Neri mentions the nail in his Discorso and Thurneysser is discussed in a 1601 letter to the priest from his friend Emanuel Ximenes.

This post first appeared on 16 August 2013.

Thévenot in India

Mirror ring with inlaid foiled glass
late 18th to early 19th c Rajasthan India.

This is the third and final installment of a series that has followed seventeenth century French tourist Jean de Thévenot from Europe to the Levant and then into Syria. We have specifically looked into his diary with an eye toward passages that mention glass or glassmaking. While our intrepid traveler had no special connection to this art, he did possess a keen, inquisitive mind; collectively, his observations about glass give us a glimpse into the state of affairs in the Middle and Far East in the mid 1600s.

We left off with Thévenot as he headed up the Tigris River toward Baghdad, in the autumn of 1663. While he was anxious to see Mughal India, actually getting there presented some difficulty due to hostilities between the Dutch, British and Portuguese, which extended to their trade operations around the world. After a first attempt was aborted, he made a strategic retreat to Isfahan and bided some time with shorter excursions from there. Finally, in the autumn of 1665 he booked passage on the originally English ship “Hopewell” recently purchased by an Armenian trader and captained by an Italian. [1] The ship departed from Basra and made port at Surat, India in January of 1666.

The city of Agra is in the Northwestern part of India, a thousand kilometers from Surat and the coast; it is known most famously as the home the Taj Mahal. When Thévenot passed through, he noted of the women “They wear a great many [rings], and as they love to see themselves, they have always one with a looking-glass set in it, instead of a stone, which is an inch in diameter.” [2]

These rings, set with a mirror, are known as “arsi” and can still be found in some areas around the country. Indeed, Sharma and Seth note in their 1997 book on contemporary regional costumes and ornaments that mirror rings were popular in the northern most reaches of India. In the western Himalayas at Chamba and as throughout India, they are still worn today. “Arsi or arsu means a mirror. An ornament with this name is a ring fitted with a round mirror or a looking-glass. It is usually worn on the thumb of the right hand. With the help of arsi, the hill woman can look at herself in the mirror and feel assured of her beauty in such places like fairs and festivals. Thus she can stealthily have a glance in the mirror whenever she desires, even in the company of males without feeling awkward.” [3]

Another reference states that in the seventeenth century arsi rings were worn by both men as well as women, but I have been unable to confirm this. In any event, they appear to have been wildly popular. On an earlier expedition through Aleppo, Syria, Thévenot observed “five or six hundred cases of [mirrored] glass” being shipped down the Euphrates River. When he expressed surprise at the rough handling, he was told “that it mattered not, though it were all broken into pieces, because the Indian men and women buy it only to have little pieces set in rings, which serve them for looking-glasses to see themselves in.” [4]

Thévenot’s first landing was in Surat on the west coast of India, about 300km north of Mumbai. In 1688, Captain Alexander Hamilton landed at the same port and recorded, “The [Muslim] women wear gold rings on their fingers, and sometimes one on their thumbs, with a small looking-glass set in it.” [5] Other travelers also noticed the rings:  In the 1660’s Frenchman Souchu de Rennefort observed similarly, “They wear also many [rings] on their fingers, and among the rest, one with a small looking-glass in it, which serves them to contemplate themselves.” [6]

The earliest account I have been able to find recounts not a glass mirror but one of metal. On 25 September 1637, ambassadors from the Danish duke of Holstein were visiting the King of Persia and were entertained by six dancing women from India. The women were accompanied by their husbands who played musical instruments. “Some of them had bracelets of pearl, others of silver, but they had all rings on their fingers, and among the rest, they had upon the thumb, upon which in the place where the stone should be, there was a piece of steel, about the bigness of a crown-piece of silver, and so well polished that it served them for a looking-glass.” [7]

As these accounts suggest, vanity may well have been the motivation for the popularity of the arsi rings, but it is worth noting that mirrors did play a role in some religious practices. Wikipedia states, “The Nizhal Thangals and Pathis have, in their sanctuary, a mirror to reflect the images [of] worshippers. […] The mirror's placement symbolizes that God is inside oneself and it is of no use to seek God elsewhere.” [8] In some Muslim weddings of Southern India, a traditional ritual is called ‘Arsi-Mushaf’ or “the mirror ring and the Quran,” in which the newly betrothed observe each other through a mirror.

Thévenot stayed in India for over a year and crossed the country to its East Coast. Finally, he returned to Surat, sailed to Persia and traveled north back to Shiraz. He spent the summer of 1667 at Isfahan, after suffering an accidental gunshot wound. In the autumn, he started north for Tabriz, but died on the way at Meyaneh on 28 November 1667.

[1] Armenians in Asian Trade in the Early Modern Era, ed. Sushil; Kevonian Chaudhury (Keram). (France: Les Editions de la MSH, 2008) p. 106.

[2]Jean de Thévenot: The Travels Of Monsieur De Thévenot Into The Levant: In Three ..., Volume 3

 (London: Archibald Lovell Faithorne, 1687)v. 3,  p. 38.

[3] Kamal Prashad Sharma, Surinder Mohan Seth: Costumes and Ornaments of Chamba (New Delhi: Indus Publishing,1997), p.113

[4] Jean de Thévenot: “The Travels of Monsieur Thévenot Into The Levant” (London: H. Clark, 1687), v.2, p.40.

[5] Alexander Hamilton, A New Account of the East Indies: Giving an Exact and Copious ..., Volume 1(London: C. Hitch; and A. Millar, 1744) v. 1, p. 165

[6] Gabriel Dellon, Jodocus Crull, Souchu de Rennefort: A voyage to the East-Indies: giving an account of the isles of Madagascar (London: D. Browne, 1698) p. 25

[7] Adam Olearius, John Davies, Johann Albrecht von Mandelslo: The Voyages & Travels of the Ambassadors from the Duke of Holstein, to the ... (London: Thomas Dring, and John Starkey, 1662), p.277

[8] Wikipedia: https://en.wikipedia.org/wiki/Ayyavazhi_rituals

Alchemist Priest

"Brother Mauritio" detail from

Tesoro del Mondo  (Treasure of the World,) 

by Antonio Neri 1598-1600, f. 19r.

The fact that Antonio Neri was both a dedicated alchemist and a Catholic priest may seem a bit odd to current sensibilities. If we take a broader view and try to accommodate history, the situation can seem odder still since in Neri's time, the late sixteenth to early seventeenth century, alchemists were sometimes portrayed as practicing sorcery. As far as the Church was concerned, sorcery was a heretical offence. In some quarters, the seemingly miraculous manipulations of alchemists to duplicate or even improve on materials found in the natural world were seen as tapping into divine powers. As the bubonic plague ravaged Europe, finger pointing at suspected culprits for bringing down the wrath of God was not terribly uncommon. Nevertheless, the fact is that Antonio Neri was both a Catholic priest and an alchemist, and in good standing on both counts. To understand how this could occur, we need to scratch beneath the surface of history a little deeper.

Taking an even longer view, we see that both religion and alchemy have been practiced for a very long time, since before recorded history. Both conferred cohesive benefits to society and both required the keeping and passing of secretive knowledge. In this light it becomes very reasonable that the two disciplines might be conducted by some of the same people. Muslims, Hindus, Buddhists, Jews, Christians, all have rich traditions of alchemy that stretch back to their beginnings. That religion and alchemy coexisted for so long is really a pragmatic issue; alchemy formed the foundation of medicine, metallurgy, the production of paints and many other arts. It was essential to even very small communities, not to mention the advent of distillation: the art of producing a good stiff drink. When a religion, any religion, was adopted into a community, the practices of the community were also adopted into the religion. From this we can infer that the ancient practices that eventually became alchemy were alive and well in the prehistoric Mediterranean tribes, in Celtic and Etruscan societies and in the Asian states long before written history. 

Now, returning to the early 1600s and Antonio Neri, many Christian orders boasted long traditions of alchemy. The Dominicans had Albertus Magnus, the Franciscans had Roger Bacon and Ramon Llull. It is true that in the fourteenth century, Pope John XXII signed a decree banning the counterfeiting of gold and silver by alchemical means, but this has often been wrongly interpreted as a general prohibition, which it was not. In fact, there is every indication that this pope, a trained physician, was well acquainted with the positive benefits of alchemy. Furthermore, the prohibition did not it stop a long line of chemical experimenters within the Church from trying their hand at gold transmutation. In a more pedestrian vein, monks in far-flung monasteries regularly maintained herbal gardens from which they distilled medicines and spirits, and made pigments for paints using alchemical methods. Monasteries were the repositories of knowledge and within their walls, alchemical texts were studied closely.

Neri's specific affiliation, his sect, within the Church is currently unknown although there are a few good guesses. His sponsor was Medici prince Don Antonio, who maintained a palace laboratory called the Casino di San Marco on the north side of Florence; this is where Neri worked at the beginning of his career. The laboratory was located directly across the street from one of two apothecaries maintained by the Dominicans. It is hard to imagine that there was not some kind of relationship between two facilities, both practicing alchemy mere steps from each other on opposite sides of the same street. This apothecary was part of the San Marco Convent complex, which a century earlier harbored Savonarola. There are strong indications that Neri’s family was sympathetic to his reform minded agenda. Savonarola sponsored the first Florentine pharmacopoeia -- a book of medicinal recipes used by physicians and apothecaries. Neri's father, who happened to be the grand duke's personal physician, presided over a later revision of the same book.

Neri's sponsor, Don Antonio, held high office in the Knights of Malta, a religious military order which reported directly to the pope and had great latitude in the types of projects it pursued. The Knights of Malta ran two churches in Florence and Neri can be connected to both.  The order traces its roots to the crusades and has various associations with alchemy such as George Ripley. One legend tells that Ripley helped to finance the knights through the production of alchemical gold. The knights followed the rule of Augustine and enjoyed a close relationship with the Augustinians.

The Augustinians counted a Francesco Neri as abbot of their San Clemente monastery near the Casino. The same abbot Francesco also worked for Don Antonio de' Medici at the Casino and may have been Antonio's brother. Antonio's aunt, Faustina, apparently entered an Augustinian convent after the death of her husband. 

But there is no shortage of other possibilities; as a child, the priest's home parish church was the Benedictine San Pier Maggiore. His father was buried at a Cistercian church, his grandfather at the Franciscan cathedral. At the end of his life, Antonio Neri's confessor was a Carmelite, but also served as the parish priest of an abbey run by the Canons Regular of the Lateran. Whichever group served as his base of operations, through Antonio Neri, they continued a very long tradition of alchemy practiced within the Church.

Waxing Moon

In Chapter 5 of L'Arte Vetraria, Antonio Neri shows how to extract salt for glass from fern plants in an evocative recipe. Fern was and still is widely abundant in Tuscany. It presented a ready source material for glassmakers of the region. Neri directs that harvesting of the plants be done in the spring:

Cut this herb from the ground when it is green, between the end of the month of May and mid June. The moon should be waxing and close to its opposition with the sun, because at this point the plant is in its perfection and gives a lot of salt, more than it would at other times and of better nature, strength and whiteness.

At first, it is tempting to dismiss this lunar influence as the product of a fertile imagination, but let us take a closer look. Tidal forces of the moon do in fact subtly affect plants, fish and animals in ways that can be measured. A closer look at Neri’s advice reveals reasoning that is hard to dismiss as mere astrological superstition. When the moon is waxing, tides rise and so do water tables. According to folklore, this is when sap rises from the roots of plants into stems and leaves. Sap carries the dissolved mineral salts required for glass. Neri also stipulates that harvesting should take place during lunar opposition. When the moon is 'opposed' to the sun, it is on the opposite side of the earth from the sun. In opposition, the moon is near full and rises as the sun sets. Plants see more light at night, leading to increased photosynthesis and growth.

In contrast, violin makers from Cremona valued high alpine spruce called moon wood. Trees were felled in the wintertime, when lunar tides were low. This minimized the amount of vibration deadening sap in the wood. In his Natural History, Pliny relates Cato’s advice on felling trees in accordance with the lunar cycle. In fact, centuries-old tradition specified lunar conditions for a host of needs from construction timbers to cheese boxes.

This post first appeared on 5 August 2013.

Weights and Measures

Ford Madox Brown,  The Manchester Murals: 
"The Proclamation Regarding Weights and Measures, 1556."

In his book L'Arte Vetraria, Antonio Neri's glass recipes depended on precise amounts specified in units as small as the 'grano,' [grain] named after the weight (mass) of a single grain of wheat or barley. In interpreting his formulas, the glassmaker must understand the quantities he used. For us, there are unfamiliar units like the 'fiasco' and the 'dita.' The dita or digit was simply the width of a finger. A fiasco or flask was the volume of a glass wine bottle, about two-and-a-quarter liters in Florence or two-thirds of a US gallon - about half of British imperial gallon. (As an aside, there are many fanciful stories of how the word 'fiasco' came to be synonymous with failure or disaster, perhaps the most believable is that the losers of competitions or bets were expected to buy the next round of drinks.)

In addition to unfamiliar units, there is the problem of standardization; a pound in Florence weighed different from a pound in other areas as close as Massa or Piedmont. Each Italian city maintained its own set of master weights and volumes to which merchants were expected to adhere. In reality, the differences were minor and may have been more attributable to politics than accuracy. Since antiquity, commodity merchants realized that if their own set of weights used in sales were ever so slightly below the norm, over time a savings would be realized, not large but significant. Towns could apply this principle as well; it paid to set standards slightly above or below neighboring towns from which one was buying or selling various goods. In truth, the differences were not great simply because successful commerce demanded that buyers and sellers could agree and strike a deal.

Even in different countries throughout Europe and the Mediterranean, we find close agreement in the various units of measure. Neri's first translator, Christopher Merrett, made an interesting substitution in his 1662 English version of L'Arte Vetraria. In chapter 132, Merrett writes "six pints of water" for Neri's "libre sei di acqua," changing pounds into pints. At first, it seems odd to be converting weight into volume, but this was perfectly valid. At that time in England, the pint was defined as exactly a pound (of wine or beer). Sailors were often each allotted a pint a day; the pint was also one-eighth of a cubic foot. (A cubic foot was equivalent to a gallon.) This system was very convenient for shipping companies who needed to calculate cargo volume and ballast in their trade ships as well as avoid mutiny by running out of beer at sea. Later, in 1824 King George IV increased the gallon from eight to ten pounds of water, invalidating Merrett's substitution.

Other conversions were more problematic. As absolute measurements varied from place to place, the size of a batch would be larger or smaller; not a big worry. However, ratios were of critical importance to a recipe. Just as in baking a cake, an entire batch of glass could be ruined by changing the ratio of materials. This sort of difficulty was especially prevalent with the size of an ounce; the troy and apothecaries system were based on a twelve-ounce pound while the avoirdupois system used a sixteen-ounce pound. When Merrett wrote his translation, England had officially been under the avoirdupois system since Henry VIII (although, In 1588, Elizabeth I complicated matters further by raising the weight of a pound by about twenty-one percent.) Meanwhile, Florence and much of Europe continued to use the troy system.

English glassmakers who wished to use Neri's book as a working document would need to know which system to use. Merrett's direct translation added a hurdle that would confuse the unaware. In order to approximate Neri's intended composition under the prevailing avoirdupois system, Merrett's "ingenious" (as he called them) British readers would need to decrease by 1/5 quantities specified in pounds, and increase ounces by 1/15.

This post first appeared on 18 September 2013.

Old Post Road

In the winter of 1603-1604, Antonio Neri left Italy to visit his friend Emmanuel Ximenes in Antwerp. There is no way to know the exact path he took, but based on the advice in Ximenes' letters and on well-established trade routes; a good estimation can be made. It is likely that Neri was starting from Pisa. The path  suggested by his friend took the priest first back east to Florence, then perhaps through Bologna, Ferrara and Padua to Venice. Ximenes offered to make arrangements for Neri to travel from Venice with traders headed to the Frankfurt fair held at mid-lent. There would have been plenty of time for him to celebrate Advent in Florence and Christmas in Venice before his caravan headed north. The group could have left as late as the end of January.

Ximenes suggested that Neri travel with the courier from Florence to Venice. He was referring to the system of coaches that delivered the mail throughout Habsburg Europe, run since the early 1500s by the De Taxis family. While the Medici and other heads of state maintained their own fast couriers for diplomatic and military messaging, the De Taxis had a monopoly on almost every other piece of correspondence, a privilege for the family that was later extended to other parts of the world by the Holy Roman Emperor. They ran an efficient system well into the eighteenth century. An elaborate series of 'posts' were set up at intervals, where tired horses were watered and swapped for fresh steeds and riders so that the journey could continue uninterrupted. Independent travelers could partake in the system for a fee based on equipment required and the weight of luggage. In Neri's time, accounts were settled at each post and travelers could elect to stay over in a town and pick up a later expedition. On well-established popular routes like between Florence and Rome, travelers could pay a flat rate that included lodging and meals. If Neri had traveled light and spoke some German, he might have completed the entire journey in as little as ten days; the time letters from Venice to Flanders took to arrive. However Ximenes advice suggests a longer excursion.

I would recommend that you should go with the courier from Florence to Venice, arriving in Venice in time that you would be able to accompany the merchants who come to the fair held in Frankfurt at mid Lent;  you  will stay there the length of the fair for fifteen days, which will not displease you for having seen it. After that, you would go in the company of other merchants to Cologne, and then with them or others, by land or sea to Holland, ending up at this city. This sea, however, is nothing more than rivers. I recently went by land to Basel and from there by water ending here. But for Your Lordship,  who does not speak the German and Flemish languages, I would consider better the way that I say, with merchants from Venice to Frankfurt and then with others by water to arrive here. 

On Embarking from Venice, the party of traders would head west, back to Padua, on to Verona and then north along the ancient trade route through Bolzano to the Brenner Pass. The journey from Venice to Frankfurt was about 600 miles (950 km). Traveling an average of 30 miles per day, they would be on the road for three weeks. Depending on their itinerary, the journey could have varied by a week in either direction. The start of the fair was mid-lent, the date of the traditional feast held three weeks before Easter. In 1604 mid-lent Sunday fell on 28 March.

Brenner is the lowest pass across the central Alps, connecting Bolzano on one side to Innsbruck on the other and was passable year round. The distance of this, most difficult part of the journey, was about 75 miles (120 km), with a vertical climb of 4,495 ft (1,370 m), almost a full mile, but all below the tree line. Assuming a slow pace for pack animals, this segment could still be completed in less than a week, stopping in Bressanone, (Brixen), then at the alpine city of Vipiteno (Sterzing), where perhaps some extra time was taken to rest and view the nearby silver mines. Gries am Brenner was just over the pass on the Austrian side. With the majestic Wipp valley (Wipptal) at their backs, the remaining journey was down hill from there. From Innsbruck, the traders would head towards Augsburg, perhaps with an excursion through Munich, which was then the capital of Bavaria. The route from Augsburg through Wurzburg to Frankfurt was riddled with small towns accustomed to hosting traders since Roman times. After a few weeks on the road, the fair at Frankfurt would have come as a welcome diversion.

At the end of the fair, a week before Easter, Neri would start the final 250 miles (400 km) of his journey. First, he would travel over land with merchants or the Ximenes family servant to the walled city of Cologne on the Rhine River. Next, he would move by water toward the sea. The northern route, along the Rhine, avoided the military conflicts between the Dutch Republic and the Hapsburg Empire. The most dangerous were between Liege and Antwerp. From Rotterdam, the inland waterways led south to Antwerp. Priest Neri may well have arrived in time for Easter Vigil.

This post first appeared in a shorter form on 21 October 2013.