The devil is in the details: turpentine varnish

Corrosion cast of bronchi and trachea, possibly from a rabbit, sheep, or dog, 1880-1890
Likely prepared by Harvard anatomist Samuel J. Mixter.
The Warren Anatomical Museum in the Francis A. Countway Library of Medicine

This post first appeared on The Recipes Project on 5 June 2018.

By Marieke Hendriksen

One of the first things you learn when you do reconstruction research is that the tiniest detail can make a difference.

Recently, I wanted to prepare an injection wax for corrosion preparations according to a 1790 recipe. Corrosion preparations are anatomical preparations created by injecting an organ with a fluid coloured wax that hardens. The organ is then lowered into a container with a corrosive substance, such as a hydrochloric acid solution, which corrodes the tissue, leaving a negative image of the veins and arteries of the organ. These preparations were made from at least the mid-eighteenth century, but because of their fragility, very few remain. As they were supposedly difficult to make, corrosion preparations were not only a way of studying anatomy, but also a tool for self-fashioning and establishing one’s status as an anatomist.

I have tried to create an injected preparation in the past.[1]It was my first attempt at reconstruction research ever, and although it served me well at the time, now I do things differently.

Most importantly, I want to stay much closer to the original recipe if possible. When we made the injected preparations in 2012, we used modern substitutes for some historical ingredients for economic reasons, and we did not have the time to study every ingredient in detail, substituting those we could not find directly with something we thought would have pretty much the same effect.

The recipe I want to use, Thomas Pole’s 1790 instruction for making a corrosion preparation, calls for a coarse red wax, made from fifteen ounces of yellow bees wax, eight ounces of white resin, six ounces of turpentine varnish, and three ounces of vermillion or carmine red.[2]The wax, resin, and pigment are fairly straightforward.

What is turpentine varnish though? Back in 2012, we ended up using just turpentine rather than turpentine varnish, and although those injections were not meant to be corroded, we ran into numerous problems. For example, it turned out to be almost impossible to keep the wax and the organs at a temperature at which we could both handle it and have it fluid enough to inject. It made me wonder whether sticking with the original recipe could solve that problem, so I set out to recreate it.

This turned out to be more complicated than expected, as there is not one standard recipe for turpentine varnish. Eventually I found a Dutch recipe from 1832 listing a turpentine varnish to finish display cabinets for natural history collections.[3]The ingredients are a pound of oil of turpentine, 8 ‘loot’ (a loot being 1/32 Dutch pound) of white resin, four loot of Venice turpentine, and ½ loot of aloe or kolokwint. Raw larch turpentine has a high concentration of volatile oils that can be distilled. The fluid part is known as oil of turpentine, whereas the residue left in the retort is usually called resin, rosin, or colophony. Oil of turpentine is the essential oil that remains after distilling raw larch turpentine. Venice turpentineis a thick, viscous exudation from the Austrian larch tree, which is not used as a varnish on its own as it becomes dark and brittle when exposed to oxygen and light. Aloe vera is widely known; kolokwint (the Dutch name for Citrullus colocynthisor bitter apple) less so. It is a plant with yellow fruits that resemble small pumpkins, which are very bitter and poisonous. That quality might explain its presence in a recipe for a varnish that is meant to ward off insects. Powdered aloe is readily available from artist’s material suppliers, so I went with that.

The varnish after 10 hours in the sun. The Aloe is the clearly visible murkiness on the bottom. Photograph: author.

The preparation of the varnish was pretty straightforward: put all ingredients in a bottle, cover, and leave in the sun for a day. The only problem was that I had to wait a week for a sunny day. When it came, I put in the ingredients and just left the bottle out in the sun for a couple of hours, which allowed me to stir the ingredients together. The aloe however did not resolve properly, and just sits at the bottom of the jar. While this might not be much of a problem when the varnish is applied to a cabinet, it makes this particular turpentine varnish unsuitable for use in my injection wax. Next time, I will make another batch without aloe and use that instead.

Why do I recount this–admittedly not very exciting–story? It shows how difficult it can be to follow a historical recipe to the letter. It also shows how much you learn from reconstruction research, even if it does not always yield the results you’d like, or as fast as you’d like.

[1]Marieke Hendriksen, Elegant Anatomy, (Leiden: Brill 2015), pp. 1-9.

[2]Thomas Pole, The Anatomical Instructor ; or an Illustration of the Modern and Most Approved Methods of Preparing and Preserving the Different Parts of the Human Body and of Quadrupeds by Injection, Corrosion, Maceration, Distention, Articulation, Modelling, &C(London: Couchman & Fry, 1790), pp. 21-5, 122-42.

[3] S. de Grebber, Over de schadelijke huisinsekten, als de huisvliegen, wespen, muggen, weegluizen, vlooijen, luizen, motten, pels-, boek- en kruidkevers en wormen, hout-, blad- en schildluizen, plantmijten enz., met aanwijzing van voldoende en proefhoudende middelen, om dezelve geheel uit te roeijen, Volume 1,(Amsterdam, 1832), pp. 52-3.

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This blog first appeared on The Recipes Project on 15 March 2018

Fermenting indigo at Ock Pop Tock, Laos. January 2018.

When you say indigo, the first thing many people will think of is blue – jeans blue. (Or if you’re me, you’ll think first of a seventeenth-century recipe to make decorative blue prunes from wax with indigo. Occupational deformation.) But historically, indigo has been used in many more ways, and to make more dye colours than just blue, as I recently discovered. Today, most jeans are died using a synthetic blue dye, but indigo dyes, made from some of the over 750 species of the genus Indigofera as well as from some other plants, have been used to dye textiles for at least 6,000 years, while other subspecies of Indigofera were traditionally used as analgesics with anti-inflammatory properties.

The term ‘indigo’ according to the OED started to occur from the sixteenth century onwards in various European languages to denote blue dyes from India (or east Asia more generally), but can now also refer more generally to dyes, violet-blue light, or blue hues. It might be argued that the term only really applies to dyes created from Indigofera subspecies, while it could also be said that indigo is any dye created from plants through the decomposition of the glucoside indican, which exists not merely in the indigo-plant, but in woad and various other plants too.

While on holiday in Luang Prabang, Laos, I took a weaving and dying workshop with Ock Pop Tock, an organization that was established to preserve the traditional Laotian craft of making hand-loomed textiles. There, I discovered that there is more indigo besides Indigofera, and that one indigo plant can give many more dyes than just blue. They also have a wonderful informative website on natural dyes. At Ock Pop Tock, the plant species used to create indigo dyes is Persicaria tinctoria, or long leaf Japanese indigo, a plant indigenous not to Japan but to China, Vietnam, and Laos. Depending on how the leaves are treated, it can be used to create blue, green, black, and mauve.

…give them a good pounding to create a dye.

Using the fresh leaves creates a green dye, fermenting them for at least five days and adding limestone as a mordant gives a blue dye. Traditionally, the Lao believed that the dye was female, and that it fermented because it attracted a male spirit. To coax the spirit, the pots containing the dye would be dressed in a skirt, and a knife placed on top of the lid to ward off evil spirits that could ruin the dye. The fermentation is actually a naturally occurring oxidation process, with atmospheric oxygen as the oxidant. Regular stirring ensures the process continues. The longer the indigo mixture is left to ferment, the darker it turns. If this mixture is boiled, it turns black. Alternatively, a rare indigenous plant, mak bow or bow vine, can be added to the blue dye to create mauve.

The end result: a beautiful scarf

As part of the half-day workshop, I got to dye a silk scarf with a dye of my choice. I love green hues and wanted to make a dye from start to finish, so I chose to dye my scarf ‘indigo’ green. This was, apart from some pretty intense pounding of leaves, surprisingly easy. I got to pick freshPersicaria tinctoria leaves in the beautiful garden, washed them, and mashed them vigorously in a mortar for about five minutes. Then I transferred the mashed leaves into a tub, added some cold water and then the raw silk scarf. After kneading the dye into the fabric for a couple of minutes, I could rinse my scarf and hang it to dry. The end result is a beautiful soft green scarf, that is not just a souvenir, but a tangible reminder of the traditional Laotian knowledge about natural dyes preserved and shared at Ock Pop Tock.

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Teaching a Perfect Knowledge in the Arts and Sciences: Robert Dossie’s chemical, pharmaceutical, and artistic handbooks

Front page to a 1796 reprint of Dossie’s Handmaid

*This post first appeared on The Recipes Project Blog on 7 December 2017*

By Marieke Hendriksen

Robert Dossie (1717-1777) was and English apothecary, experimental chemist, and writer. Within just three years, he published three very successful handbooks: The elaboratory laid open (1758) on chemistry and pharmacy for ‘all practitioners of medicine’, Theory and practice of chirurgical pharmacy (1761) for surgeons, and The handmaid to the arts (1758), which taught ‘a perfect knowledge of the Materia Pictoriae’ such as painting, gilding, and japanning. Gibbs (1951, 1953) has written a short overview of Dossie’s life and work, with a focus on his role in the Society of the Arts, but paid no attention to the cohesion of his seemingly divergent work.

Lowengard (2006) has briefly noted that Dossie used a form typical for books about materia medica for his book on the arts, grouping the contents according to techniques employed as well as by the media to which they might be applied, yet his work has never been thoroughly analyzed. Did Dossie indeed transmit a way of structuring and presenting practical knowledge in text from one realm to another? Recipe collections and how-to books before the eighteenth century were often a mixture of medicinal and artisanal recipes and instructions, and the boundaries between medicine, chemistry, and the preparation and application of artist’s materials often so fluid as to be almost non-existent.

Moreover, some earlier printed books on painting and dying techniques did employ the format of a systematic discussion of materials and their preparations, followed by their application, for example Willem Goeree’s 1760 Verlichterie-kunde  What was novel about Dossie’s Handmaid of the Arts though was the combination of this way of presenting practical artisanal knowledge, his attempt to be encyclopaedic in his collection – listing the uses of the same base materials in the production of various artistic and decorative objects, and his very intentional use of the term ‘Materia Pictoriae’.

Rubia tinctorium (madder), one of the many plants that was both materia medica and materia pictoria

The latter appears to have been an attempt to subtly elevate the status of the visual and decorative arts by paralleling the materia pictoriae to the materia medica. Finally, the intended audience gives us more insight in how Dossie understood his own work. From the preface of the book, it appears that Dossie did not so much aim at the people creating visual and decorative objects, but at the professional preparers of artist’s materials, of whom he wrote: “a much greater share of knowledge in natural history, experimental philosophy, and chymistry, is required to the understanding the nature of the simples [sic], and principles of the composition, in a speculative light, than is consistent with the study of other subjects more immediately necessary to an artist.” (p. vii-viii)

In eighteenth-century England, high street chemists and druggists were evolving from preparers and sellers of chemical substances to compounders, stockists, and sellers of drugs and dispensers of medical advice, and it is in this light that Dossie’ work and his division between materia medica and materia pictorial must be seen. Did Dossie intentionally and successfully adapt and implement formats and language traditionally used in one field (medicine) for the organization and transmission of practical knowledge in text to others (chemistry and the arts)? To me it appears that in his mind, materia medica and materia pictoriae were both branches on the tree of chemistry, and that his corpus, which we now tend to see as divergent, was actually a cohesive body of work to him and his contemporaries.


Dupré, Sven, ed. Laboratories of Art : Alchemy and Art Technology from Antiquity to the 18th Century. Archimedes 37. Cham [u.a.]: Springer, 2014.

Gibbs, F.W. “Robert Dossie (1717–77) A Further Bibliographical Note.” Annals of Science 9, no. 2 (1953): 191–93.

Gibbs, F.W.  “Robert Dossie (1717–1777) and the Society of Arts.” Annals of Science 7, no. 2 (1951): 149–72.

Lowengard, Sarah. The Creation of Color in Eighteenth-Century Europe. Columbia University Press, 2006.

Worling, Peter M. ‘Pharmacy in the Early Modern World, 1617 to 1841 AD’, in Making Medicines: A Brief History of Pharmacy and Pharmaceuticals, ed. by Stuart Anderson (London: Pharmaceutical Press, 2005), pp. 57–76.



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The Making of Technique in the Arts: Concepts and Practice from the Sixteenth to the Twentieth Century

*This blog was originally published on The ARTECHNE Project Blog on 26 September 2017*

By Marieke Hendriksen

“Peintures en huile, en miniature et encaustique,” Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers, vol. 8 (plates) (Paris, 1771). Plate I: Painting, Atelier, Paint Pallet and Brushes.

The terms ‘technique’ and ‘technical’ are used widely in relation to art, art history and science today, both to refer to the technical analysis of artworks and to a more holistic analysis of creative processes. Yet we do not have a history of the shifting meanings of the term ‘technique’ in the arts and sciences. The word ‘technique’ was a neologism in the vernacular, and started to appear in treatises on arts and sciences from the middle of the eighteenth century. Rooted in the Greek techne, which was translated routinely as ‘art’ until the mid-eighteenth century, technique referred to processes of making or doing and their products. Such processes had been described to previously as ‘art’, ‘methods’, ‘manners’ or ‘mechanics’ in the vernacular, and they were recorded in text with the intention of documenting and/or transmitting practical skills and knowledge.

On 26 and 27 October, Sven Dupré and I are hosting an international workshop at Utrecht University with the aim of bridging the gap between the changing concept of technique and the practices currently described by it. Questions we seek to answer are for example: how was what we now call ‘technique’ in the arts and sciences described and understood before the term took hold? More specifically, how were techniques in the arts described between 1500 and 1900? What kind of written sources can we distinguish, which terms were used to describe and instruct technique in various languages, and who were the intended audiences of these works?

Hans-Jörg Rheinberger will give a public keynote lecture, entitled “The Hands of the Engraver – Albert Flocon meets Gaston Bachelard”

Moreover, we will look at the linguistic history of technique in the arts, with questions such as why the term ‘technique’ first emerged around 1750, and what did it mean initially to artists, art theorists, and natural philosophers? Is there a connection with the emergence of categories such as aesthetics, fine art, craft, mechanics, and technology? Did the meaning of ‘technique’ and related concepts vary between periods, practices, and European languages, and how can we use data and concept mining to understand this? What do we mean by ‘technique’ in relation to art now, and can we use the same word to describe historical knowledge and practices?

Another issue closely related to the understanding of the concept of ‘technique’ in the arts is the development of so-called somatic language. Somatic language to describe measurements and sensory characteristics of materials traditionally played an important role in technical art texts, but seems to become rarer or more standardized over time. This kind of language guides the reader’s posture, as well as the use of their own body, and tools and materials, yet it is often unspecific and metaphorical (‘shift your weight’, ‘a handful’, ‘like yoghurt’), and meanings and interpretation can vary wildly in different languages, times, and cultures. How did the use of this kind of somatic language change in Europe between 1500 and 1950? What was the influence of standardization on conservation practices?

During the workshop, we will discuss these and related questions in panels of specialists from a variety of fields, such as history, art history, intellectual history, philosophy, and linguistics. Each interdisciplinary panel will focus on a particular concept, but there will also be ample time for exchange between the various panels.

Limited seating is available, please contact if you are interested in attending.  

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Transmitting technique between disciplines: the anatomical models of William Rush (1756-1833)

*This blog was originally published on The ARTECHNE Project Blog on 9 March 2017*

A travel grant from the Wood Institute at the College of Physicians of Philadelphia recently allowed me to do research in their library and archives. Established in 1786, the College holds a wonderful collection of manuscripts and printed works. As I am particularly interested in the transmission of art technical knowledge in the long eighteenth century between medical men and people we would now describe as artists or craftsmen, I started looking for connections between such people in Philadelphia. I did not have to search long, for Philadelphia in 1800 had a population of only 41,220, but it was a fast-growing trading hub with two medical colleges, and an art academy was about to be established. This meant that many Philadelphians in the middle and upper classes knew each other personally – some were even related.

William Rush, Tragedy, 1808. Pine (originally painted). Copyright: Philadelphia Museum of Art.

Philadelphia-born William Rush had started his career as a carver of ship figureheads, learning the trade from his father and the famous Edward Cutbush. He was one of the founders of the Pennsylvania Academy of the Fine Arts (est. 1805), and from the early nineteenth century onwards, he created a number of sculptures for public places in Philadelphia. Caspar Wistar (1761-1818), professor of chemistry and the institutes of medicine at the College of Philadelphia, was a skilled maker of anatomical preparations and models, which he created by injecting organs with wax. However, when the number of students attending his classes greatly increased in the early decades of the nineteenth century, he decided he needed something more dramatic as a teaching aid: enlarged models of human anatomy, which would be visible even at the back rows. Realizing that this surpassed his own modelling skills, he turned to Rush, who made at least twenty models for him.

Model of the Right Maxilla by William Rush, c. 1808

As is so often the case when people are physically close, no primary written records –such as letters- remain of this collaboration between Wistar and Rush. However, their collaboration shows that there were strong connections between medical men and visual artists and craftsmen in Philadelphia around 1800. It is likely that Wistar and Rush already knew each other before they started working together. Not only was Philadelphia’s population fairly small, William Rush was a full cousin of a colleague of Wistar’s, the famous Philadelphian physician and professor of chemistry Benjamin Rush (1746-1813). Moreover, Wistar came from a family of craftspeople himself: his grandfather and namesake (1696 –1752) was a German-born

William Rush, Portrait bust of Caspar Wistar, ca. 1812-13. Terracotta. Copyright: Pennsylvania Academy of the Fine Arts

glassmaker. Both Benjamin Rush and Caspar Wistar studied in Edinburgh, and the latter corresponded with Thomas Pole, a fellow Quaker and the Philadelphia-born author of the 1790 The Anatomical Instructor, a handbook that describes, amongst others, how to make anatomical preparations and models from a variety of materials – although wood was not one of them.

So although in this case there is no evidence that Wistar taught Rush anatomy or that Rush taught Wistar practical skills for model making, it is clear that they must have been very aware of each other’s knowledge and skills, and it is rather unlikely that they never learned anything from each other. In any case, Rush successfully transmitted his technique from one discipline to another: from artistic sculpting to anatomical model making.

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A forgotten chapter in natural history: the taxidermy of man

*This blog originally appeared on the Recipes Project on 9 March 2017*

By Marieke Hendriksen

Having written a book on eighteenth-century anatomical collections, I know a thing or two about historical techniques for preserving (parts of) the human body. As I am interested in natural history collections more generally, I also did some research on the preservation of animal bodies, and even took a taxidermy course myself. However, recently I realised that the preservation of human and animal bodies were historically even closer connected than I had imagined. Yet ideas about which parts of the human body could and should be preserved, and how, diverged greatly, particularly when it comes to skin, or taxidermy. Taxidermy, from the Greek τάξις (taxis) and  δέρμα (derma – I am adding those for people who may not read Greek script), literally means ‘the arranging of skin’.

Fragment of an engraving of the anatomical theatre of Leiden University, early 17th century, showing visitors who appear to discuss a human skin. Contemporary engraving by Willem Swanenburgh; drawing by Jan van ‘t Woudt (Johannes Woudanus).

There are a few known cases of attempts to preserve human skins in their entirety before 1800 – for example, there was a human skin in the Leiden anatomical theatre in the seventeenth century – but that wasn’t stuffed, and such attempts appear to have been altogether unsuccessful. If human skin was preserved, it was mostly small pieces, which were used to study things like skin colour and structure, tattoos, or pathologies. By the end of the eighteenth century, the preservation of an entire human skin in a lifelike pose was of little interest to anatomists. Normal internal anatomy would be studied through dissection and the creation of preparations and skeletons, and pathologies of the skin could be preserved by making preparations of small sections of skin. As healthy skin can be studied perfectly easily in live subjects, there was little reason to pursue the taxidermy of man. This is reflected in anatomical handbooks like Thomas Pole’s 1790 Anatomical Instructor (reprinted in 1813), which gave detailed directions for numerous methods to preserve parts of the human and animal body, including entire heads and foetuses, but did not say anything about how to preserve only skin. On the contrary, Pole advised to remove the cuticle from a head that was to be preserved,  as this would give ‘a brightness to the complexion’.[1]

Jeremy Bentham’s ‘preserved’ head is not on display, but stored in an environmentally controlled safe. Copyright: UCL.

However, with the growing popularity of taxidermy – the mounting of animal skins in lifelike poses – and the rise of physical anthropology in the early nineteenth century, there were a number of experiments with human taxidermy, the most famous of which was probably Jeremy Bentham’s unsuccessful attempt to have his body made into an ‘auto-icon’ after this death. Then there was ‘el negro’ or ‘the negro of Banyoles’, whose faith was described by Dutch author Frank Westerman in his 2004 book El Negro en ik (‘El negro and I’). The remains of this young African San man were stuffed by two taxidermists, the French Verreaux brothers, in the 1830s, and remained on display in a local Museum in Banyoles, Spain, until 1997. Eventually his remains were send for burial in Botswana in 2000. Jules Pierre (1807-1837) and Jean Baptiste Édouard (1810-1868) Verreaux created taxidermy specimens of exotic animals for their father’s Parisian shop in natural historical objects, Maison Verreaux, and, as ‘el negro’ shows, used human bones for his models.

The head of the figure in ‘Arab Courier attacked by lions’ sits detached from the rest of the diorama during restoration work. Copyright: Nate Smallwood | Tribune – Review

For a long time, ‘el negro’ was the only known case of nineteenth-century human taxidermy. However, a recent discovery suggests that the Verreaux brothers used human remains more frequently. In 2016, a human skull was discovered in a mannequin that was part of an ensemble made by the Verreaux studio. Formerly known as “Arab Courier Attacked by Lions”, it was restored and returned to display at the Carnegie Museum of Natural History in Pittsburgh under the title “Lion Attacking a Dromedary”. Although apparently no attempt was made to use human skin in the Pittsburgh diorama, these cases show that there was little reticence when it came to using human materials for taxidermy displays in the nineteenth century, particularly when the human in question was considered ‘exotic’. This is supported by the fact that a popular contemporary taxidermy manual, aimed specifically at museums and travelers, opened with a paragraph on the impossibility of applying taxidermy to man successfully. The book, written by the naturalist Sarah Bowdich (née Wallis, later Lee, 1791-1856) saw six editions – the first in 1820, the last in 1843.

After listing the necessary tools and giving a number of recipes for the cleansing and preservation fluids used in taxidermy, Bowdich opened the section on ‘the preparation of mammalia’ with a somewhat disappointed-sounding statement:

1. Of man 

All the efforts of man to restore the skin of his fellow creature to its natural form and beauty, have hitherto been fruitless: the trials which have been made have only produced mis-shapen, hideous objects, and so unlike nature, that they have never found a place in our collections. 

Bowdich went on to discuss the life-like wet preparations made by Amsterdam anatomist Frederik Ruysch (1638  – 1731) as ‘without doubt (…) very useful to science’, before switching to a description of a more successful practice – the preservation of skeletons. Given the tragic history of ‘el negro’ and many other violently obtained human remains in museum collections, it is a cold comfort that the naturalists of the nineteenth century failed at the taxidermy of their ‘fellow creature’.

[1] Pole, Thomas. The Anatomical Instructor ; or an Illustration of the Modern and Most Approved Methods of Preparing and Preserving the Different Parts of the Human Body and of Quadrupeds by Injection, Corrosion, Maceration, Distention, Articulation, Modelling, &C. London: Couchman & Fry, 1790: p.84.

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Preserving and modelling the body: technique in anatomical practice and visual arts at the Royal College of Surgeons of Edinburgh, 1700-1850

A guest blog I wrote for The Royal College of Surgeons of Edinburgh (RCSEd) Library and Archive – looking forward to this project very much!

The Royal College of Surgeons of Edinburgh (RCSEd) Library and Archive

Our guest blog post is from Marieke Hendriksen, a postdoctoral researcher at Utrecht University. Marieke will be joining us in October here at the RCSEd Library and Archive on a Wellcome Trust Research Bursary. Her research is a study on practices and resources used by the members of the Royal College of Surgeons of Edinburgh, to preserve and make models of the human body in the period 1700-1850. Look out for related events and future blogs!

The art of modelling [in plaster] trenches upon that of the artist, and, as everyone knows, is practiced by a number of persons as an art. Professors of this branch of science are in every large city, and I recommend to do as I did, viz. visit the studio of the artificer in stucco. All in this line in Edinburgh, at least, I found most communicative, and happy at all times to explain everything, and much more of…

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