Dear Readers,

As you may have seen elsewhere, in mid February my wife and I suffered the loss of our home in a fire, in the hills of central Massachusetts. The good news is that we got out safely and had no animals in our care at the time. The fire crews were able to contain the fire from spreading, in what turned into a 3-alarm, 5-hour-long ordeal in subzero temperatures; they did amazing work, and no one was injured. The bad news is that all of my physical historical materials and research of 30 years have gone up in smoke. As a result I have decided to suspend this blog for the time being. It will remain online as a resource for those interested in the history of glass and glassmaking in the seventeenth century and beyond. I do intend to resume writing when I can, but for now my time and energy are required in getting us back on our feet.

Friends are providing temporary shelter for us nearby and our intention is to rebuild as soon as possible. To those who have reached out with a steady hand, to those who have opened their wallets, and offered advice in our time of need, we thank you from the bottom of our hearts. In what are already difficult times for all of us, you have made a huge difference in our lives.

Paul Engle
6 March, 2021

Friday, June 3, 2016

Neri's Contribution

L. C. Tiffany  window "Education,"
in which religion and science are in harmony.
(Click to enlarge)
Recently, a reader asked: Can you comment on the scientific contributions of Neri? Or on the scientific significance of alchemy? Both are excellent questions, to which I hope I can provide reasonable answers.

Antonio Neri (1576-1614) is a fascinating character to be sure and it is worth briefly sketching out his life; he was born in Florence, Italy into a wealthy patrician family. His father was the personal physician to the grand duke of Tuscany and his mother came from a family of prominent lawyers who served Michelangelo among others. Evidence suggests that Neri was educated locally. At about age twenty-two he was ordained as a priest in the Catholic Church. The timing of his first known manuscript (devoted to “all of alchemy”) [1] strongly implies that the Church, as well as his father and the Medici court all took part in his preparation for the unusual vocation of alchemist.  

Neri’s involvement in glassmaking seems to have started close to the turn of the seventeenth century, when he was employed by prince Don Antonio Medici at his “Casino,” a combination palace, arts venue and experimental laboratory where “secrets of nature” were pursued. The priest would go on to work at a glasshouse in Pisa and spent seven years in and around Antwerp in Belgium, where he continued working on both glass and alchemy.

The most visible scientific contribution was the publication of his book, L’Arte Vetraria (the art of glassmaking) in 1612. [2] This was the first book on the subject of glass formulation to be published anywhere. His collection of recipes opened up to the public what had been closely guarded trade secrets known only by practitioners of the art, and generally passed down through families. The book was written explicitly to be intelligible by general readers and as such it gained a steadily growing popularity among experimenters. The book was eventually translated into English, Latin, French, German and Spanish (and recently Japanese). It served as a sort of bible for both artistic and scientific glassmakers for over two centuries. 

While Neri cannot be said to have stated any laws of nature, discovered chemical elements, or invented new instruments, indirectly, his work did help support all of those things. We can say with certainty that prominent figures took note of his work; the same year of his death, 1614, Galileo was requested to send a copy of Neri’s glass book to Federico Cesi, the founder of an early scientific society in Rome, who was delighted with its contents.[3] Galileo ordered special optically clear glass from Neri’s former employer in Pisa, although the outcome is not recorded. We also know that Neri went about creating his formulas through methodical experimentation; from letters received by Neri from a close friend [4], it becomes clear that he tried many, many variations of a glass formula before settling on a particular version. We know he closely followed the work of other experimenters; he was a devotee of the late Swiss physician Paracelsus, who espoused a careful observational approach to both medicine and chemistry. His alchemical assistant Agnolo della Casa took copious laboratory notes, albeit in cryptic shorthand that historians continue to grapple with.[5]

Neri was part of a rapidly growing shift toward empiricism. The central idea was that nature’s secrets could be revealed through careful scrutiny. This sounds patently obvious today, but in Neri’s time the mindset was different. Great store was put into the work of earlier writers and philosophers. Even his own father worked strictly by principles that had been set down by the ancients. Neri’s father treated disease by balancing “humors” in the body which carried the essences of the four Aristotelian elements. If a patient did not respond then it was reasoned that other unknown forces must have been at work. Similarly, Galileo was dismissed out of hand by some for claiming different masses fell to the ground at the same acceleration. His claims varied from established teaching and therefore, his critics argued, were somehow faulty. Seeing was not always believing. 

In the early seventeenth century, the world was conceived of very differently than it is today. Human intellect was not any weaker, but investigators did proceed from a different set of assumptions. Our current understanding of the world developed from much more than a new set of facts; it required a whole evolution in how we perceive. Back then, what made materials different from each other, metals for instance, was thought to be the essences of air, fire, water, and earth infused in them; the transmutation of one material into another was thought to be a very reasonable possibility. Also, it was not a given that a chemical operation performed under the same conditions would always produce the same results or even in the same amounts, nor that they would produce the same outcome tomorrow as yesterday. The principles of invariance and conservation were only starting to take shape. In a manuscript written shortly before his death, Neri claimed to have had successfully produced gold in the laboratory, but only once, and years earlier. [6] It was his contention that successful transmutation was determined ultimately by divine providence, which he called "the gift of God." 

But times were changing, albeit slowly; within several decades of Neri’s death, philosopher Baruch Spinoza referred to nature’s “immutable order.”[7]  Spinoza was a glass lens grinder by profession with a copy of Neri’s book on his shelf. In the same time frame, Isaac Newton would publish Principia, [8] laying out basic laws of nature. Even amidst these fundamental breakthroughs, Newton worked at alchemy and physicians of his time still treated disease by balancing so-called humors. When Neri’s alchemy manuscript [9] surfaced in the 1870s, George Farrer Rodwell published a letter in the journal Nature pronouncing him a “sensible chemist.” [10]

Neri thought of himself first and foremost as an alchemist and there is little doubt that his work in that realm is what he would have preferred to be remembered. As it turned out, his book on glassmaking is what secured him a place in history. His clear description of materials and lucid procedures endeared him to scientific investigators throughout the period where medicine, chemistry and optics grew by leaps and bounds and for which glass was an indispensable material. At the same time, the book’s use for artistic pursuits and especially for making artificial gems fueled sales and ensured its ready availability.


[1] Antonio Neri, Libro intitulato Il tesoro del mondo di Pietre Antonio Neri - che tratta di Alchimia con diverse figure, non solo di forni, uasi, et instrumenti chimici, ma altre figure intorno alle miniere di tutti i metalli, MS Ferguson 67, GB 0247, Glasgow University Library, Special Collections, 1598–1600.
[2] Antonio Neri, L’Arte Vetraria, distinta in libri sette, del R.[everendo] P.[rete/ padre] Antonio Neri fiorentino. Ne quali si scoprono, effetti maravigliosi, & insegnano segreti bellissimi, del vetro nel fuoco & altre cose curiose. All’Illvst.mo et eccell.mo Sig., Il Sig, Don Antonio Medici (Florence: Giunti 1612). 
[3] Letters from Federico Cesi to Galileo concerning Neri: BNCF, Gal. 90, f. 112r; cf.: Ed. Naz., XII, p. 12, n. 964. Cesi 1614b: BNCF, Gal. 90, f. 131r; cf.: Ed. Naz., XII, p. 15, n. 968.
[4] Emmanuel Ximenes, Letters of Antonio Neri, BNCF 2.1.391 (1601–1611).
[5] Agnolo della Casa, Manuscripts BNCF: Ms. Palat. 867 1592–1618 19 volumes.
[6] Antonio Neri, Manuscript, Biblioteca Nazionale Centrale di Firenze: Ms. Conv. Soppr., B.3.16. Discorso sopra la chimica (che cosa sia, e sue Operazioni del R.[everendo] P.[rete] Antonio Neri Sacerdote Fio.o) (1613).  Also see Maria Grazia Grazzini, “Discorso sopra la Chimica: the Paracelsian Philosophy of Antonio Neri” in Nuncius, 2012, v. 27, pp. 411-467.
[7] Baruch Spinoza, Tractatus, Theologica-Politicus (Hamburg: Henricum Kunrath, 1670). See also Theological-Political Treatise, J. Israel, M. Silverthorne,eds., (Cambridge: Cambridge Univ. Press, 2007).
[8] Isaac Newton, Philosophiæ Naturalis Principia Mathematica. London: Royal Soc. Press, 1687. Also see The Principia: The Authoritative Translation and Guide, Mathematical Principles of Natural Philosophy. Isaac Newton (Author), I. Bernard Cohen (Translator), Anne Whitman (Translator), Julia Budenz (Translator). UC press, 2016.
[9] op. cit. Tesoro del Mondo.
[10] G. F. Rodwell, “On An Unpublished Manuscript by Antonio Neri” in Nature, (8 September 1870), v. 2, no. 45, pp. 370–371.

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