The Blue Project

“The deeper the blue becomes, the more strongly it calls man towards the infinite, awakening in him a desire for the pure and, finally, for the supernatural.”

Wassily Kandinsky

The Blue Project is my ongoing investigation into the color which conveys the most depth and dimension both physically and metaphorically. I constantly struggle to pin down blue and understand it to the fullest extent in order to harness its effects in my own work. What you see here are examples of my explorations in blue though visual art as well as my historical analysis of the color, with emphasis on the Middle Ages.


Even now, the poignancy of the color blue strikes a chord of mystical curiosity within us. We associate it with sadness, depth, and darkness; and contrarily, peace and spirituality. These connotations are deeply rooted in themes of mysticism, primarily with religious or ritualistic origin. The Middle Ages became a climatic evolution of associations regarding the color, giving it the lasting effects we experience now. We find blue’s otherworldly aura through fear and reverence which culminates in a viewing of blue from the vantage point of someone lesser than, peering upon something so completely deep it is impossible to understand it completely; yet this mystery is precisely what intrigues us to both the color and to the spiritual world. The figurative meanings we attach to blue mirror the our basic understanding of what blue is: a reflected light that visually recedes against other colors and becomes a conveyor of depth. These treatments of blue paralleled with the medieval mind’s awe of the esoteric divine leads to the viewing of blue as the most mystical, holy or unholy, of all the colors.

I. Establishing Blue

Upon examining the color itself and its formal qualities, one perceives blue as a conveyor of physical depth and space (stemming from our basic association of blue with the sky and sea). Both, while seem flat, have become an indicator of depth above or below a two-dimensional surface, and we in turn associate the color with the same understanding of hidden three-dimensionality. By nature, blue light tends to naturally recede in contrast to other colors, red in particular, as proven by the illusion of chromostereopsis (depth created by two flat contrasting colors). Rarely do people see red as receding; most often blue forces itself into the background and enlarges the dimensionality of the space. Already, we can derive an intuitive meaning of depth from the color blue and, as our poetic nature permits, we allow depth to become both literal and figurative in our association with blue. Depth evokes a fear of the unknown, yet simultaneously a longing to understand. In that sense the dichotomy surrounding our reaction to the color is born, translating to the later fear and reverence within the Catholic Church.

Blue is hypothesized to be only recently perceived by the human eye. Lazarus Geiger traced the literary references of the color back to ancient times upon noticing Homer’s unusual depiction of the Aegean as a “wine-red sea.” He found references to blue no sooner than Ancient Egypt, the first people to produce blue dye from either woad or “Egyptian Blue,” (calcium copper silicate, also known as cerulean from the Roman caeruleum), and from there branched a written awareness of blue once mankind could create the hue themselves. Egyptian Blue was the first man-made pigment,³ establishing blue as an unnatural entity. In every language, blue is the last color to be assigned a word and is accepted to have been the last color ever perceived by the human eye; even still, referencing Jules Davidoff’s research regarding the Himba tribe in Namibia and their inability to differentiate blue from green, there are people to whom blue has not yet materialized in the

mind’s palette. Only two percent of our cone cells respond to blue light, again providing room for misunderstanding and intrigue. Already we see fundamental patterns of mystery surrounding blue that become embedded in its meaning. Until human beings created an artificial blue for ourselves with Egyptian Blue, the color had no signifier or differentiation, and therefore did not appear to be born from the natural world. From its birth in the human eye, blue is founded in practices of alchemy, creating rich pigments from sand, copper, and natron; and a deep blue from the yellow woad flower.

II. Ancient Context

The Egyptians used woad and indigo to dye cloth for mummification, an early correlation of blue with death and the Afterlife. Not only did the use of Egyptian Blue spread across the Mediterranean, but that of indigo as well. Indigo has a blue-purple hue that has long been debated in terms of belonging in the category of blue. In Rome, the differentiation between blue and purple was a culturally crucial, especially in terms of the dye’s origin. Indigo was seen as its own color but was most likely associated with purple rather than blue, or considered its own category entirely; the color rivaled the royal purple of Rome and held as highly as the Tyrian purple developed by the Phoenicians, derived from an expensive process of harvesting a marine snail. The Romans held an acute association of color with its origin, which we see in both the names and symbolic treatment. When a Roman sees a color, they prioritize the specific dye and material over the simple visual qualities of the color. Color becomes a material to them without our everyday exposure to synthetic dyes of unknown association. They were less interested in categorizing hues into color groupings as they were in connotations of material. When regarding both woad and indigo as blue, we forget that to the Roman eye they had not been grouped together as such: they were vitrum (woad) and indicum (indigo). The word vitrum is also the latin word for glass, supposedly linked by the scarification and tattooing rituals of the Picts, as seen in Julius Caesar’s campaign in Britain. The word indicum evolved from a Greek word meaning “Sindhi dye,” referring to the Indus Valley in modern-day Pakistan, where the dye was sourced before it came to the Mediterranean via the Silk Road. In both instances, the Latin words refer to the sources or the materiality and use of each color, viewing it as an object married to it’s physical material than a color with a separate material application. Here lies the vague differentiation between blue and purple in Roman society; the separation happened on a case-to-case basis depending on the specific dye.

The best way to observe this separation and viewing of color as a material is by comparing purple with woad blue. During his 55-54 BCE campaign to Britain, Julius Caesar writes that the Britons “dye their bodies with woad, which produces a blue color” (Caesar, Gallic War, V.14). There are a few problems regarding this phrase such as its reference to the Picts (“painted people” in Latin), who lived in Northern Scotland, while Caesar would have been in present-day Kent. However, there are plentiful written instances of the Roman interaction with woad in Britain by Propertius, Pliny, and Martial that confirm a Roman association with woad and barbarism. The role of woad in Rome existed primarily in the lower class due to these associations and the fact that woad was accessible and possibly produced within Rome. Blue was the Roman color of darkness and the poor, and having received an awarness and perception of blue from the Egyptians, this may be from the cryptic Egyptian practice of woad-dyed mummification cloth. However indigo, with all its similar characteristics to woad, was reserved for the upper class; the journey from India made it a rare extravagance, and it was more often than not grouped as a purple hue, if not its own color. Regardless, indigo was distinctly separated from woad blue and enjoyed the same treatment as purple.

III. Medieval Europe

Medieval Europe finalized many of the societal connotations of blue that exist today. While blue’s divine aura does appear in isolated cultural tropes, magnifying Medieval Europe’s treatment of certain pigments allows for an intricate comprehension of the uses of blue within the contemporary Western world; this time period is also abundant with primary sources of blue’s evolution which, while specific to Europe, do reflect the worldly viewing and treatment of blue.

Woad made itself prosperous within medieval Europe while indigo remained a scarce luxury until much later, as indigo could not be cultivated locally. Woad had been used throughout Europe for centuries and was nothing new to the working class; the earliest evidence of commonly used European woad existed in the Stone Age, primarily in Northern Europe and Scandinavia. The use of woad expanded rapidly throughout the continent and by the Middle Ages was established as a dying staple and a flourishing industry. Medieval dying revolved around 3 essentials: woad (blue), weld (yellow), and madder (red), which we see listed in Chaucer’s The Former Age as common staples. Woad began as the color of the peasantry; not only was it cheap and easy to produce, but its long fermentation process, partly in barrels of urine, produced a lasting odor that turned up the noses of the wealthy. The stench was so terrible that as late as 1585, Queen Elizabeth had decreed The Proclamation Against the Sowing of Woade and set a radius around her estate which was to be woad-free until a solution for the odor was designed. An entire class of woad workers (or “waddies” in old English) was born, along with the nickname “blue nails” which can be translated from multiple languages across Western and Northern Europe, and referred to the blue residue stained onto the hands of dyers.

The practicality of this industry was further fueled by the antibiotic properties of woad and its ability to treat wounds and reduce fever. What we call medicinal science, a medieval monk would call philosophy, as the lines between science and religion or conceptual thought had yet to be drawn; most scientific advances were performed by monks yearning to understand the universe in an effort to be closer to God. Both the medicinal value and the innate alchemic nuance from the process of woad dying drew the industry under the wing of the Catholic Church, the head of philosophical (in the medieval sense) development. The Church had an attraction to the mystical and the unknown, for that is where they might find God; and in their efforts to uncover His instructions for the universe they developed equally an affinity and a fear for all things miraculous. What draws attention to a miracle is the unexplainable, allowing for belief in another character or force acting upon the situation. A mystery begs us to fill the informational gap with a story befitting of the situation, often concluding in faith; or, if faith is taken further, to trust that you might be able to prove that story through the medieval practice of philosophy. This all applies to the Church’s management of the color blue, beginning with the protection of the Blue Nails. The process of woad dying involves a stick and caldron, and the act of turning a yellow flower into a blue dye. This fed into the fascination of alchemy as a means of searching for eternal like through the means of creation of new material, such as God’s original creation, and secured the Church’s interest. Throughout Germany, France, and England, remnants of attached woad houses may be seen on churches and cathedrals such as from the 10th century in York and most notably from St. Augustine’s Monastery in Erfurt, Germany. The monastery dates back to the 13th century but the woad trade and houses were not firmly established until the early 15th century. By that point, Erfurt had become a woad center and depended on the trade for its survival. In towns such as Erfurt, woad had built a partnership with Catholic practices and monastic ritual and livelihood, giving the monks a mystical aura that might later be associated with witches as they stir their cauldrons. This is the path in which a lowly, barbaric plant such as woad travels to the protection of the Church.

The uses of woad extended past dying the garments of the peasantry and into the realm of finer art, yet still within the confines of religious practices. The Lindisfarne Gospels, circa 700 A.D. in Northumberland, exhibit intricate illuminations using woad as blue pigment.

Illumination practices soon replaced woad with ultramarine, a luminous pigment made from finely ground lapis lazuli, a precious stone then only mined in Badakshan, Persia (modern day Afghanistan). Ultramarine had been in use for centuries but did not become wholly popular until the Middle Ages, when it was more expensive than gold and was treated as such.

Woad regained a heightened amount of prestige and a place within the European nobility in the 13th and 14th centuries. The French House of Valois established the standard of blue with golden fleur-de-lis robes to adorn their monarchs and blue begins its royal association. The center of France’s woad industry was Toulouse, and today visitors can still see the woad-stained shutters of medieval architecture. The monarchical interest in woad forced its popularity in court life, and woad’s reputation went from rags to riches. The color “King’s Blue” comes from French woad, and eventually evolved into the iconic blue spotted with gold fleur-de-lis we see constantly in representations of French monarchs within medieval illuminations.

This sudden jump in the reputation of woad blue as well as the prominence of the luxurious ultramarine uplifted the color blue in a general sense to the status of royalty and in turn, of saints and icons. At the same time in history, beginning primarily with King Richard I of England, parallels between the monarch and God are drawn and Kings began to enjoy a saintly status. Blue fit perfectly into this relationship, as woad blue’s association with royalty matched the ultramarine garments of the Virgin. The monarchs were often depicted with halos, so such a holy color was only fitting for their garments and symbols.

The common theory for the blue robes of the Virgin Mary is simply that ultramarine was the most precious of all pigments and therefore deserving to be worn by her. While this is true, much more influenced this trend than simply the value of the material. When reading through Latin hymns, Mary is almost always described in relation to the stars, the sky, or the sea. In Alma Redemptoris Mater, she is addressed as “Loving Mother of the Redeemer, who remains the accessible Gateway of Heaven, and Star of the Sea.” It is no coincidence that Mary is always partnered with specifically blue-colored natural entities, all of which may refer back to the previous discussion of our instinctual viewing of blue’s inherent depth because of our relationship with the sky and the sea. In Ave Maris Stella, we see a similar example: “Hail, Star of the Sea, Loving Mother of God, and Virgin Immortal, Heaven’s blissful portal!”²¹

Within most versions of the Bible, blue is the least mentioned color; however, that in itself yields its importance. Blue was sacred and reserved for particular instances, and in the Old Testament was the color of the Israelites: “Speak to the people of Israel, and bid them to make tassels on the corners of their garments throughout their generations, and to put upon the tassel of each corner a cord of blue” (Numbers 15:38-39). The significance of blue seems to always appear through mentionings of cloth: “spread over [the Ark of the Covenant] a cloth all of blue’ (4:6); “And over the table of the bread of the Presence they shall spread a cloth of blue (4:7).” The color is also presented as the robes of the tabernacle. Already, a familiarity around blue’s holy aura was established, and so naturally it continued with the iconography of the Virgin. If blue represents the otherworldly mysteries and miracles that man cannot explain, then Mary–the virgin mother of the child of God–perfectly fits the description.

The link between Mary and her blue can be confirmed by 1260 when Louis IX opened the new Chartres Cathedral, illuminated in a blue glass alchemically designed specially for the Virgin’s image. The cathedral itself is dedicated to Mary since it houses her tunic as a relic, and so “Chartres Blue,” as the glass is called, became synonymous with the Virgin’s robes. The alchemists who produced the color, in particular the shade used in Notre Dame de la Belle Verrière, developed an obsession around this specific shade of blue. The recipe has since been lost and has yet to be replicated.

The connection between Mary, Heaven, and blue is strengthened by evidence of paintings on cathedral interiors. Gothic cathedrals, despite their cryptic grey-scaled ambiance now, were originally adorned in saturated patterns and colors. Such themes can be seen in modern restorations or in rare instances, where some of the paint has survived. The trope of the star-strangled blue ceilings arrived at the same time as the association with Mary and the color blue was strengthened by the use of ultramarine, Chartres Blue, and the birth of King’s blue. The architecture of gothic cathedrals emphasizes height and reaching vertical motion as portrayed by columns and thin sections of wall divided by upwards sweeping windows. The intention behind this is to connect to Heaven; a sort of streamlined visual to God. They furthered the illusion of indefinite height by utilizing the receding nature of blue while also imitating the sky and referencing the robes of the “Star of the Sea…Heaven’s blissful portal,”²¹ the Virgin, who is also seen in the common adornment of stars across the sweep of blue. When one looks up in prayer, the prayer is a plea, usually for an answer to a question, and is propelled by a fear of the unknown. So, we tilt our heads up to the unknown itself, the very source of our fear, and place within the deep recession of blue a faith. The faith is only possible because the depth of the blue allows for our minds to imagine endless possibilities, and so the unknown inspires equally hope and fear. The Dome of Santa Maria Assunta Cathedral in Siena flaunts a surviving example of the deep blue roof littered with textile-like stars, the dome itself being a later addition to the Cathedral and having been erected in the 14th century.

Blue rears its head again in the work of medieval nun and poet Hildegard of Bingen in 12th century Germany. She primarily describes scenes from her own personal visions in her book Scivias, which includes illuminated poetry and, in the last vision, a collection of songs. The songs, in reflection of Gothic architecture, reaches towards creating a spacious envelopment through simpler, monophonic chants and crisp, deep reverberations. The melisma affects the listener almost like gentle waves lapping on the surface of a much more profound force, such as the blue oceans and Heavens of the illustrations. Her vision “the Trinity” describes a visit from Jesus who radiated in blue light. It is heavily debated whether Hildegard herself had a hand in illuminating the iconic image of the Blue Christ-figure, though most can agree she had influence on the creation of all the manuscript’s illuminations. In dissecting this second vision of Part Two, the focal point lies on completely blue figure with open hands radiating in a mandala-like halo. The first ring is a golden ochre and is then enveloped by the second ring which is a muted light blue. The importance of this light blue is emphasized as it breaks through the ochre ring at the top of the figure’s head and outlines his body in a cooling radiance. The background of the image is then a solid blue. The stream of blue aura spilling from the crown of the figure feels reminiscent of Hindu and Buddhist depictions of the 7th chakra; the text itself also provides similarities:

A wheel was shown to me, wonderful to behold…Divinity is in its omniscience and omnipotence like a wheel, a circle, a whole that can neither be understood, nor divided, no begun, nor ended….Just as a circle embraces all that is within it, so does the Godhead embrace all.” ²⁷

Again the intuitive spiritual nature of blue and the coloring of Heavenly auras as blue comes through, based simply on the human perception of the the color and the figurative connotations this naturally evokes. The more isolated instances of blue partnered with divine connection, the more it leads us back to that simplified scientific understanding of blue as naturally receding and gaining its mystical affirmation through its alchemic birth. The image of a blue circle in particular appears across isolated religions, and as seen in Hildegard of Bingen’s work, they usually appear in semi-abstracted forms such as her visions from God in “Scivias 2.1: The Redeemer.” The manuscript provides many illustrated examples of the mandala form in relation with her divine communication, often rendered with her own image in the corner transcribing the blue orb that fills the center of the page.

IV. The Intuitive Aura of Blue

The spirituality of the color blue is so innate in its formal qualities and biological perception that it appears in visual representations of divine connection across isolated religions. In Hinduism, the god Krishna is depicted as blue-skinned, contributing to his both holy and terrifying presence, lifting him higher than human status. We again observe a separation between blue and indigo in the labeling of chakras. Both the throat chakra (Vishuddha) and the Third Eye chakra (Ajna) come across as blue, but are distinguished as harnessing different spiritual associations and are shown as two totally separate colors. Within meditation in multiple Eastern religions, the concept of the “Blue Pearl” emphasizes the connection between the color blue and the essence of the soul. The Blue Pearl is used as a tool to come into contact with one’s inner being through meditation, if one may see a luminous blue dot appear in the darkness behind their eyelids. In finding this blue light, we find our own consciousness according to the writings of Swami Muktananda:

“…the Blue Pearl [is] the subtlest covering of the individual soul….When we see this tiny blue light in meditation, we should understand that we are seeing the form of the inner Self. To experience this is the goal of human life. [The Blue Pearl] is tiny, but it contains all the different planes of existence.”

The idea of something being simultaneously tiny while “[containing] all the different planes of existence” is reminiscent of the same dichotomy revolving around the color blue in Christianity: the conflict between something being so tangible and yet so unknown and vast, such as the very idea of god or faith. Evagrius Ponticus, a Greek monk from the 4th century, wrote of a meditative state in which the goal was to reach an understanding of the trinity, signaled by a sapphire-blue light:

“If one wishes to see the state (katastasis) of the mind (nous), let him deprive himself of all representations (noe¯mata), and then he will see the mind appear similar to sapphire or to the color of the sky. But to do that without being passionless (apatheia) is impossible, for one must have the assistance of God who breathes into him the kindred light (Skemmata 2).”

Isaac of Nineveh, a 7th century hermit who had left his place as bishop in search of self-purification through constant prayer, called “sapphire . . . the color of heaven” based on his visions. A similar passage describing a sapphire hue may be found in the Septuagint translated from Hebrew to Greek:

“And they saw the place, there where the God of Israel stood, and that which was beneath his feet, like something made from sapphire brick and like the appearance of the firmament of heaven in purity” (Exodus 24:10).

All three texts share the same color descriptor: sapphire (Greek sappheiros, Hebrew sappir) which, rather than referring to the semi-precious stone, actually translates back to our familiar lapis lazuli. Eusebius recounts that the Egyptians found their original Creator in the figure Kneph, a winged, egg-like orb flanked with serpents and painted that same deep blue as Hildegard of Bingen’s blue mandalas from Scivias. The trope of non-anthropomorphic beings in the context of their often blue appearance points to highlight the qualities of the being rather than the physical being itself: hence, further emphasis on the aura achieved by its coloring.  The blue orb, pearl, or light becomes less of an entity and more of a sensation that was difficult to visually pin down. However, it is this lack of full understanding that cultivates fascination; thus begins the concept of fear and reverence, a cultish fetish of longing within the unknown.

The aural sensation of blue forces us to reference the basic understanding that blue conveys depth. The physical ability it has to recede in contrast with other colors and its novelty to the human eye translate easily into the poetic forms in which society has built for blue: that of mystery and wonder.  Within the context of Medieval Europe, blue is born into a nuance of fear left over from ancient times, and as a natural reaction to the fairly recent perception and understanding of it. However, a humanistic fetish for the mysterious drags blue into the light of the Church amidst the monastic facilitation of alchemy. The liturgical link further established by the use of ultramarine as worth for the Virgin Mary and, in turn, for monarchs as they achieved a godlike status. The Catholic Church exercises the divine nature of blue through architecture, music, painting, and text: any way to artistically render what they see as in line with God in its mystery. Blue puts on display the unified dichotomy of the holy and unholy as simply the “mystical,” the unknown territory where the love and fear of God lies.


  1. Kitaoka, A. Chromostereopsis: Advancing color and receding color. 2002. Accessed November 27, 2017.
  2. Schuemann, Nancy Loyan, Paul Seaburn, Brett Tingley, and Brent Swancer. “Blue was the Last Color Perceived by Humans.” Mysterious Universe. March 11, 2016. Accessed November 27, 2017.
  3. 2015, Paul Brack October. “Egyptian blue: more than just a colour.” Chemistry World. October 01, 2015. Accessed November 27, 2017.
  4. MacDonald, Fiona. “Humans Didn’t Even See The Colour Blue Until Modern Times, Research Suggests.” ScienceAlert. Accessed November 27, 2017.
  5. Holmes, Rachel. “Why blue is the costliest colour.” The Guardian. April 17, 2015. Accessed November 27, 2017.
  6. Balfour-Paul, Jenny. Indigo in the Arab World. S.l.: Routledge, 2016.
  7. Marzano, Annalisa. Harvesting the sea: the exploitation of marine resources in the Roman Mediterranean. Oxford: Oxford University Press, 2013.
  8. Moffet, Amanda. “What did the Picts really wear?” ScotClans | Scottish Clans. August 24, 2015. Accessed November 27, 2017.
  9. Clark, Robin J.h, Christopher J. Cooksey, Marcus A.m Daniels, and Robert Withnall. “Indigo, woad, and Tyrian Purple: important vat dyes from antiquity to the present.” Endeavour 17, no. 4 (1993): 191-99. doi:10.1016/0160-9327(93)90062-8.
  10. Grout, James. “Roman Perceptions of Britain.” Roman perceptions of Britain. Accessed November 27, 2017.
  11. Roberts, Mike. History of Woad in Europe by Teresinha Roberts. Accessed November 27, 2017.
  12. Brunello, Franco, and Bernard Hickey. The art of dyeing in the history of mankind. Vicenza: Neri Pozza Editore, 1973.
  13. Magnusson, Sally. Life of pee: the story of how urine got everywhere. Aurum Press, 2011.
  14. Condra, Jill. The Greenwood encyclopedia of clothing through world history. Westport, CT: Greenwood Press, 2008.
  15. Tessman, Rima. “Woad Archives.” Rima Tessman. Accessed November 27, 2017.
  16. Brown, Nancy Marie. Abacus and the cross: the story of the pope who brought the light of science to the dark ages. New York, 2012.
  17. Harvey-Chadwick, Terry. “The Making of the Lindisfarne Gospels.” SV Educational Services. July 01, 2014. Accessed November 27, 2017.
  18. Moorey, P. R. S. Ancient mesopotamian materials and industries: the archaeological evidence. Winona Lake, IN: Eisenbrauns, 1999.
  19. Knecht, Robert J. The Valois: kings of France, 1328-1589. London: Hambledon Continuum, 2008.
  20. Artelisa. “Art history, symbolism and legends.” The Famous Blue: History of Color # 5- the Middle Ages. January 01, 1970. Accessed November 27, 2017.
  21. Jeffers, Ron, Gordon Paine, Ethan Nash, and Joshua R. Jacobson. Translations and annotations of choral repertoire. Corvallis, Or.: Earthsongs, 1988.
  22. “Why is the Blessed Virgin Mary always wearing blue?” – Worldwide Catholic Network Sharing Faith Resources for those seeking Truth – June 24, 2017. Accessed November 27, 2017.
  23. Bromiley, Geoffrey William. The International standard Bible encyclopedia. Vol. 1. Grand Rapids, MI: W.B. Eerdmans, 1979.
  24. Chartres: the Virgin Mary’s Seat on Earth. Accessed November 27, 2017.
  25. “The Duomo – The Cathedral of the Assunta.” Siena OnLine. Accessed November 27, 2017.
  26. Ecumenicus. “Ecumenicus.” Hildegard of Bingen – Man in Sapphire Blue or The Trinity: A Study in Compassion. January 01, 1970. Accessed November 27, 2017.
  27. “Blue in Spirituality.” The Blue Movement. Accessed November 27, 2017.
  28. THE BLUE PEARL. Accessed November 28, 2017.
  29. Harmless, William, and Raymond Fitzgerald. “The Sapphire Light of the Mind: the Skemmata of Evagrius Ponticus.” Theological Studies.
  30. Nicholson, Philip T. “” Religious Visions of Light. 2011. Accessed November 27, 2017.
  31. Conway-Jones, Ann. “The divine colour blue.” OUPblog. October 07, 2014. Accessed November 28, 2017.
  32. Yucatan, It’s Ancient Temples and Places.” Transactions of the New York Academy of Sciences 6, no. 1-8 Series I (1886). doi:10.1111/tnya.1886.6.issue-1-8.

Additional Sources

Brown-Grant, Rosalind. Christine de Pizan and the moral defence of women: reading beyond gender. Cambridge: Cambridge Univ. Press, 2003.

Brown, Nancy Marie. Abacus and the cross: the story of the pope who brought the light of science to the dark ages. New York, 2012.

The Interpreter’s Dictionary of the Bible: An Illustrated Encyclopedia. Nashville, TN: Abingdon Press, 1964.

Jones, Lindsay. Encyclopedia of religion. Detroit: Thomson Gale, 2005.

Knecht, Robert J. The Valois: kings of France, 1328-1589. London: Hambledon Continuum, 2008.

Morton, Jill. Blue. Accessed November 27, 2017.

Orna, Mary Virginia. The Chemical History of Color. Heidelberg: Springer, 2013.