The oldest light we can observe, the cosmic microwave background radiation, is nearly 14 billion years old. One of the defining traits of light is that it cannot truly be owned, at least not yet. In a sense, trees can archive light temporarily through photosynthesis and transform it into chemical energy.
A line can be said to span two ends of a spectrum of light: sunlight, the natural and warm light that is about 8 minutes and 19 seconds old when it reaches Earth, and light from distant stars that has traveled for thousands of years, on the one hand, to light from artificial sources or reflected light, on the other hand, that reaches us in nanoseconds.
So we see one axis representing the distance light travels and another axis covering the range from natural to artificial light.
The word “artificial” is interesting in this context because, the word presents itself to us, much like light, unbidden. It originates from the Latin artificialis, which in turn traces back, just as light moves outward, to artificium.
This leads us back to the root ars (art, skill) combined with facere (to make, to bring forth).
Lead white is produced by exposing lead plates to vinegar fumes and carbon dioxide. This process forms a white crust on the lead, which is then scraped off and used as pigment. Around 1840, zinc white was invented, and titanium white followed in 1919.
Unlike the ochre, hematite, manganese oxide, and charcoal of ancient cave paintings, these pigments are artificial and human-made, recalling Derrida’s concept of the pharmakon.
Producing pigments transforms natural substances into something artificial. They are toxic, potentially lethal, yet they also represent a technology that enables new forms of art.
Object #1 – Paint Fragment of Degas
The original painting is currently on view at Glyptoteket in Copenhagen as part of the exhibition Degas’ Obsession, running through November 29 [2025].
Object #2 – White Layer
“White Layer” consists of a white-toned digital canvas composed of fourteen digital layers, each created from tiny fragments of a CCD-based photograph of the paint pigment extracted from Degas’ Dancers Practicing in the Foyer.
“People can often be heard exclaiming, “Look at that natural light,” even while standing in artificially lit museum rooms.
Object #1 reveals a structure resembling geological strata. It is a very small fragment taken from the painting by Edgar Degas painted around 1882, and photographed through a Zeiss microscope (a process that uses artificial light) using a method called X-ray fluorescence (etymologically derived from the mineral ‘fluorspar’) spectroscopy (XRF).
So we have the literal (the title of the painting, the painter’s name), the mineral (the pigments), and the artificial (the creation of a representation of a scene that never existed at a single moment in time, but was instead the result of years of reworking.
The fragment was then photographed again with a camera using a CCD sensor, which offered a new perspective on the light. The combination of the microscope, camera lens, and CCD sensor created an image of something that Degas himself never saw as a visible object; yet, through this process, it was transformed into an object in its own right.
The artificial light that Degas worked under, whether from gas lamps or early electric sources, illuminated pigments that were themselves toxic due to their lead content.
More recent research has shown that it is possible to stop light by deforming the structure of two-dimensional photonic crystals. This could pave the way for quantum computers and groundbreaking methods of data storage.
The second object is entirely digital and inorganic, offered as both a reference point and a counterpart to the tiny paint flake from Degas’ Dancers Practicing in the Foyer.
The Getty Conservation Institute has described the method in connection with a similar analysis being done on the ‘The Milliners’ after an X-ray had shown several phases of rework, including the erasing and adding of persons:
“Because XRF is an X-ray technique, information is gathered simultaneously from all the paint layers; therefore, elements may be detected from a ground layer, together with those from overlying paint layers. If the painting has a complicated layer structure (as the X-radiograph indicates is likely the case for The Milliners), it is usually necessary to remove small samples for additional analysis in order to more fully understand the painting’s construction.
Samples taken from paintings are barely visible to the human eye (their size is less than 1 mm, typically on the order of only several hundred microns). Working under a microscope and in collaboration with a conservator, the scientist will take samples using fine surgical tools. Sometimes merely a scraping is required, but more frequently samples of all the paint layers are taken and mounted to reveal a cross-section of the painting’s stratigraphy. An ideal cross-section sample will contain all the layers of a painting from the ground layer to the final varnish.”
“From elemental analysis of the individual layers, it was determined that the ground layer is composed of lead white and barytes; the dark layer above it of lead white, bone black, and barytes, while the bright red particles are vermilion. The light brown layer towards the right of the sample is lead white and iron oxide earths (red ochre by visual examination), with associated minerals. The bright central layer is red lead followed by a lead white layer with chrome green and red ochre particles throughout. The thin dark layer at the top is lead white with iron oxide earths (again, red ochre by visual examination)”
— The Working Methods of Degas: The Milliners, The Getty Conservation Institute, 2008
Based on similar technical analyses, researchers could establish that Degas started working on ‘Dancers Practicing in the Foyer’ a lot earlier than previously thought, and that he worked on it, adding and removing layers and motifs, for close to 30 years, a process which might, in psychoanalytic terms, be described as hypercathexis.
The painting contains up to 14 layers of paint.
Greimas’ Semiotic Square
The two primary terms are Butterfly (S1) and Moth (S2). The Butterfly carries day, brightness, display, the body seen; the Moth carries night, obscurity, drudgery, the body at work. Everything below follows from that opposition.
Moving to the sub-contrary terms, Not-Butterfly (∼S1) embodies No Day/Darkness, the hidden, pre-revelation state, the pupa or the shadow, while Not-Moth (∼S2) signifies No Night/Brightness, pure illuminated clarity.
When combining the primary terms, the Complex Term (S1 and S2) becomes Transition/Transformation, encompassing the complete life cycle where night meets day.
Finally, the Neutral Term (∼S1 and ∼S2) is Stasis/Unformed: neither day nor night, no figure and no motion. Its object on this page is the ground layer described by the Getty — lead white and barytes, laid down before any image, the surface in the condition it holds for as long as nothing is painted onto it.
Silk does not belong at the neutral term. It is not inorganic and it is not inert; it is what joins the two primary terms. The fibre is a protein, fibroin, extruded by the larva of Bombyx mori, a moth. The tutu is the moth’s product worn by the butterfly.
And the thread is continuous only if the metamorphosis is prevented. Reeled silk requires that the moth never emerge: the cocoons are stifled with the pupa inside, because an insect cutting its way out severs the filament and destroys its usable length. The Butterfly-aspect of the costume is purchased by arresting the insect at the stage before flight — which makes ∼S1, the hidden pre-revelation state, permanent by design rather than transitional. Millennia of selection have left the domesticated adult flightless in any case. A moth that cannot fly dresses a body trained to simulate flight.
Applied to Degas’ ballet dancers, the opposition sets the Butterfly-aspect (S1) of the idealised, graceful performance on stage against the Moth-aspect (S2) of the backstage foyer.
The dancers shown in the foyer are often captured in vulnerable, gruelling and objectified poses that reveal the hidden, darker aspect of their profession, aligning with the moth’s symbolism of drudgery and concealment while challenging the illusion of effortless beauty presented on stage. The opposition is not only symbolic. It is a supply chain: the costume is made of the term it is worn to conceal.
One caution about the square itself. French has no lexical opposition between butterfly and moth; papillon covers both, and a moth is a papillon de nuit. The distinction this reading depends on is available in English and in Danish (sommerfugl / natsværmer), and not in Degas’ own language. What French supplied instead was the term used for the youngest dancers at the Opéra: petit rat.
A third silk, neither insect nor fibre, is on the flax page: hørsilke, the Danish name for a parasite made entirely of thread.
