No commentary on the pictures of Pia Fries can overlook the question of paint, which is emphasized so unmistakably in her works. And all commentaries demonstrate how difficult it is to talk meaningfully about paint, which Fries presents as a material that has stripped off all connection to reference, sense, and meaning. It has always been difficult to talk about paint and color, whether in the field of optics or in the arts, poetry, or music. In the first modern theory of painting, writtenin 1435/36, Leon Battista Alberti included a small sectionaboutcolors and theirharmonies, in which he expressed the following wish: “I should prefer that all types and every sort of colour should be seen in painting for the great delight and pleasure of the observer.”1 Then he made the first comments on combining and contrasting colors to enhance beauty: “There is a certain friendship of colours so that one joined with another gives dignity and grace. Rose near green and sky blue gives both honour and life. White not only near ash and crocus yellow but placed near almost any other gives gladness. Dark colours stand among lights with dignity and the light colours turn about among the darks.”2
The divide between color as a phenomenon of light, which was of interest to the world of optics and painting, and paint as a material, in which authenticity, price, fineness, and technical use were important, created difficulties. Johann Wolfgang von Goethe’s treatise Theory of Colours was published in two volumes in Tübingen in 1810. This extensive discourse on color by the famous writer found little favor because it was posited against the authority of Isaac Newton, who, in his Opticks (1704), had introduced the theory of the splitting and measurability of light. Goethe wrote in the introduction that he was not interested in defending his version “with fights and arguments,” and he justified the rejection, which was not at all appropriate, with the following statement: “From time immemorial it has been dangerous to treatof colour; so much so, that one of our predecessors ventured on a certain occasion to say, ‘The ox becomes furious if a red cloth is shown to him; but the philosopher, who speaks of colour only in a general way, begins to rave.”3 In the second section of the preface, Goethe used a somewhat strange paraphrase, after having made the assertion that it would be useless to try to “express the nature of a thing abstractedly.” This is followed by the restricting definition: “The colours are acts of light; its active and passive modifications,” which leads to the expectation of being able to draw conclusions about light from colors.4
Color remained a difficult subject for physicians and philosophers, for painters and art theoreticians. The fact that paintings acquired sensual attraction only through colors brought them under suspicion of appealing to the lower senses instead of to the intellect, as was assumed to be the case for drawings. The elevation of coloration by Charles-Alphonse Dufresnoy and by Roger de Piles to the “soul of painting” reflected a transitory position in the seventeenth century in favor of color, which was undermined again in Neoclassicism by the adherents of drawings. Even in 1867, Charles Blanc, in his persistently influential Grammaire des arts du dessin, established a hierarchical order of drawing and painting that was sexually discriminating: “Drawing is the masculine sex inart, colorinitis the feminine sex.”5 For the superiority of form over color, Blanc referred to assumptions about laws of nature: “Things are defined by their form, whereas color just creates variations, and perception relies above all on form and not on color.”6 These statements presented prejudices that became deeply rooted for a long time, and they were the continuation of unfruitful campanilismi (parochialisms) such as drawing againstpainting, Florence against Venice, Poussinagainst Rubens, Ingresagainst Delacroix, etc. In his book Chromophobia, from 2000, David Batchelor summarized all these devaluations of color: “Chromophobia manifests itself in the many and varied attempts to purge colour from culture, to devalue colour, to diminish its significance, to deny its complexity.”7
Pia Fries said in an interview in 2007: “My painting is about the power and energy of the paint itself, which, of course, forms itself in order to transform into something new.”8 The keywords that appear in this one sentence are important for the artist: power, paint material, self-formation, and transformation. Fries had been a student in the sculpting class of Anton Egloff at the School of Applied Arts, Lucerne, from 1977 to 1980, and then attended Gerhard Richter’s master class atthe Düsseldorf Art Academy until 1986. In an exhibition organized by the Kunstmuseum Düsseldorf in 1986, she showed seven panels [ fig. 1 ], each 285 × 85 cm.9 On six of the panels, colored structures can be seen, which have a root or base zone at the bottom and then strive upward, trunk-like, finishing at the top end in a pointed or rounded shape. On the seventh panel the direction is reversed: the elongated structure impacts on the lower edge of the picture. Within the structure, the directions are reinforced through lines, shapes that sprout out, or zigzag lines. From these suggestive directions one can imagine what it is like to see forces or energy inshapes. Thepanelshaveno specified designation. The description Untitled in the catalogue does not elicit any connection of forms and words. Associations with forms of nature (tree trunk, for example) or of culture (totem pole) are suggested in the structures striving upward, while the falling-down form is similar to a bomb. In the other cases, the ornamental character of the representation prevents associations from being specified.
The revealing interview from 2007 also contains a reminderof Joseph Beuys. Through meetings with the artist of social sculpture and in discussion sessions, it became clear to Fries that the “transformation of force fields and streams of energy, material consistence and fluctuation”10 were important to her, but less so the messianic sense of mission. With materials such as felt, grease, or honey, Beuys made warmth and energy visible and tangible in actions and installations. With these works of artby Beuys, the links between contemporary artistic practice andold ideas of power and good or evil forces of pictorial works, which had never been completely discarded, were taken up again and presented to the public in ritualized performances.11 “As far as I am concerned, it is not the task of painting to illustrate or make images, but to release energies and follow their currents,” Fries stated in the 2007 interview.12
Can one talk meaningfully about forces or energies in the case of colors or forms in pictures? When talking about forces or energies, does one remain on a metaphorical level or does one merely reinforce the mystification of the magic of the pictures? Is the situation, when talking about forces, similar to the way in which Paul Klee expressed matters in his first Bauhaus lecture, from 1921/22, when talking about movement? He said: “In the first place, what do we mean by movement in the work? As a rule our works don’t move. After all, we are not a robot factory. No, in themselves, our works, or most of them, stay quietly in place, and yet, they are all movement.”13 This talk of movementinpaintings is metaphorical and paradoxical, and the perception of movementin paintings could be ascribed to suggestion and autosuggestion, which have a long tradition with respect to art. In the Praise of Folly, Erasmus of Rotterdam raised the issue when the Stultitia – Folly – explains the unhappy fate of people who cannot be deceived. Illusion and opinions can make people happier than facts, which the Stultitia proves, among other things, witha board thatis splattered withred and yellow paint, butis takenby anartloveras anoriginal of Apelles or Zeuxis: “The possessor of a dreadful daub in red and yellow paint who gazes at it in admiration, convinced that it is a painting by Apelles or Zeuxis, would surely be happier than someone who has paid a high price for a genuine work by one of these artists but perhaps gets less pleasure from looking at it.”14 This line of argument from Erasmus is underhanded, because at that time, originals of Apelles or Zeuxis no longer existed, as everybody knew.
Charles Baudelaire, defending Eugène Delacroix from the supporters of the beautiful outline, wrote in 1855: “A good drawing is not a hard, cruel, motionless line enclosing a form like a straitjacket. Drawing should be like nature, living and restless. […] Nature shows us an endless series of curved, fleeting, broken lines.”15 In the irregular, in the ebb and flow, in the breaking off and starting again, we recognize the trace of the moving hand in the grain line of the drawing.
The equivalent of the line in a drawing is the touche in painting, in which the origin of the work from the hand remains visible.16 The touche, the visible and mostly pastose brushstroke, was allowed in the sketch up to the middle of the nineteenth century but was frowned upon in painting, with a few exceptions, until Delacroix ignored this aesthetic requirement and Baudelaire asserted in 1845 that a “spiritual, important, and well-placed brushstroke” has an immeasurable value.17 Against the expectation that color could be spiritualized by its immaterialization, Gustave Courbet was one of the first in the nineteenth century to decisively counter this position by applying paint in thick layers with the palette knife or throwing it onto the canvas and modeling the cliffs or spray plastically with paint. The consequences were drawn by the Impressionists, Vincent van Gogh, the Fauves, the Expressionists, the American Expressionists, and the many who paid homage to the grand geste or the action painting, and who allowed the origin of the painting in arm and hand movements to remain visible.
It is more difficult to invoke and describe the dynamics of planes than it is the dynamics of lines orpatches of color. The energy of planes withalignedorcontrasting movements was exploredby Kandinsky, Delaunay, Klee, and many others. Previously, movement in painting was essentially linked to the presentation of a moving figure, so that movement could be interpreted from the action or the narration. With Kandinsky and others the problem arose of suggesting dynamics in the picture without recourse to a figure or action, and also of creating the possibility of not binding movement to the trace of the hand movement. The solutions were color compression and color dilution in a plane, contrasts of light and dark and of complementary colors, different curvatures of the surfaces, repetitions and scaling down or enlarging, combination with aligned or contrasting arrows, among other means.
In her book Das Material der Kunst, in which she wrote an alternative history of Modernism, Monika Wagner dedicated the first chapter to paint as a material.18 She pointed out the contradictory development between the gigantic dimensions of technical reproduction, through which all materiality and all haptic qualities of the works are smoothed out, and the new evaluation of paint as a material with which many artists are involved. According to Wagner, contemporary art attempts to overcome “the aesthetic standard of the transformation of the paint material into an appearance of color.”19 For art since 1960, Wagner has identified a tendency toward a “shift in significance from form to material.”20
Heinz Liesbrock, in his essay on Pia Fries from 2007, wrote that she begins at degree zero, at the fundamentals of painting. Paint is understood not only according to its appearance but as a “physically defined, emphasized mass […], characterized by weight and a special consistency.”21
A large-scale panel such as zander [ p. 72 ], from 1993, displays vibrating and rising masses of color on a white ground. The wedge shape of paintrising from the bottom edge snakes upward with its red and black notches almost to the middle of the picture. An arm of blue, yellow, and red pushes out to the left, crosses through a standing yellow mass, and collides with a violet post with a red support, set obliquely into the picture. On the other side, a red area shoots off from the wedge of paint to the right, which is covered over with a chaotic mass of paint that develops to the right and ends up ina rising, serrated colorrelief of whitishviolet. Around a yellowy gray empty space, paint swirls back into the middle, meeting a wild mass of yellow, red, and blue, by which it is distracted and led upward. This is roughly how the paint masses and their movements can be described. There is nothing to connect it to the zander, unless you are reminded of the movement of a fish, but the association with snake movements would seem to be closer.
Like all works from the 1990s by Pia Fries, zander has a sweet and light colorfulness comprised of primary colors and their mixtures into secondary colors. Dark colors are not present. The material of paint is presented as a bright, plastic matter, which could perhaps be referred to as a fiery-sweet, elemental matter of painting.
The idea of a work, a picture, forming itself is perhaps the most difficult thing to imagine, unless one pays homage to the new mischief in art history, to the mystification of the self-reflective or self-conscious picture. The notion of self-production is associated with those ideas that stand in contrast to the planned conception and methodically guided execution of an artistic intention. The main ideas are those of furor and inspiration, by which artistic work is supposedly controlled, and that of automatic transcription. According to both ideas, the consciousness of the artist is not intended to assume any control over the creative process.
One embodiment of this interpretation of creative production was the action painting of Jackson Pollock. In a wood-shingled barn on Long Island, he laid the canvas on the ground without any idea or plan of what he wanted to produce. With his fluid paints, with his paintbrush and sticks to spray the paint, and with perforated tins for the dripping, the painter worked on the canvas from all sides. His movements were very rapid, and the painter worked himself into a kind of creative frenzy. His movements responded to the traces that they had left behind and tried to follow where the crossover and overlaying of the traces were drifting. The work began to determine the movements of the painter. Pollock commented on this process: “When I am in my painting, I’m not aware of what I’m doing. It is only after a sort of ‘get acquainted’ period that I see what I have been about. I have no fears about making changes, destroying the image, etc., because the painting has a life of its own. I try to let it come through. It is only when I lose contact with the painting that the result is a mess. Otherwise there is pure harmony, an easy give and take, and the painting comes out well.”22
This was no longer about systematic creation, as was the rule in the arts and one to be expected, as long as the deviation from the preliminary outline or the correction through pentimenti made up the whole extent of the unplanned interventions, for instance. With Pollock, it was also about the furor of about half an hour, which allowed the exchange between him and the work being created. But also involved is the idea that for a work being created, the artist becomes his medium all the more as he helps it to find its own life. The archetype of this idea of artistic activity was provided by the legendary sculptor Pygmalion, whose request is granted by the goddess Venus: she brings to life his statue, with which he has fallen in love.23
Is such a process meant when we talk about self-formation? In the second principle, there is also the idea that painting must follow the flows of energy that have been released by the artistic action. This is a process in which action and reaction are supposed to become entwined. The process remains secretive, since the artistic production has for a long time discarded all rules. Wassily Kandinsky wrote in his book Concerning the Spiritual in Art, published in December 1912: “The work of art is born of the artist in a mysterious and secret way. From him it gains life and being. Nor is its existence casual and inconsequent, but it has a definite and purposeful strength, alike in its material and spiritual life. It exists and has power to create spiritual atmosphere.”24 This is an esoteric or vitalist interpretation, but we must remember how we talk about pictures – namely, as if they could do something or have a certain effect, as if they were beings, as if they had power, could move or even think about themselves. Metaphorical language and the projection of intentions are combined into a re-demonization of the picture.
Inthe years 1679 to 1683, Maria Sibylla Merian(1647–1717), the daughterof the copper engraver and publisher Matthäus Merian, published her book Der Raupen wunderbare Verwandlung und sonderbare Blumen-Nahrung (The Miraculous Transformation and Strange Flower Food of Caterpillars), in the inherited publishing house. With this book, Merian founded the study of insects in Germany, which she had begun at the age of thirteen withanexaminationof silkworms. Twenty yearslater, sheundertookatwo-year journey to Surinam, with the aim of researching plants and animals in part of South America. After she returned to Amsterdam, Merian transferred her drawings to large-scale watercolors on parchment, which served as models for her etchings. The book, with sixty copperplates of insects and fruits in Surinam, appeared in 1705 in Amsterdam underthe title Insects of Surinam: Metamorphosis insectorum surinamensium, reprinted in 2009 by Taschen.25 Merian’s plates combine the precise reproduction of insects and plants with an ornamental grouping into artistically colorful arrangements on white paper. Picture 11, Korallenbaum [ fig. 3 ], forexample, shows a branch rising slightly obliquely upward, with open and closed blossoms. In the corners at the top left and lower right, male and female specimens of the butterfly Arsenura armida are pictured. Caterpillars in various stages crawl along the leaves and stems. The larva stage and the empty cocoon lie on a stem beneath the female butterfly.
In her variations based on Merian, Pia Fries transforms the motif of the exact imitation into an illusion of shattered flagstones by tearing up facsimiles of the Merian watercolor prints, then gluing them and pushing the parts to the edges or corners of the picture. On the flagstone fragments, plants, fruits, and insects are displayed in a lifelike way, similar to Merian’s. Snakes of paintmove between the flagstones, orcolored fruits orcolorfantasies hang down. The paintmaterial moves between the fragments on which natural beings are imitated.
In her tisch variations, Fries revives another form of trompe-l’oeil: namely, the quodlibet popular in the eighteenth and nineteenth centuries, an optical-illusion compilation of all kinds of objects on a tabletop or painted board, painted in a genuinely deceptive manner. In her picture tisch dover 1 [ fig. 3 ], several examples from Maria Sibylla Merian’s Erucarum Ortus, the book of plant and insect images published in 1718 in Amsterdam with 154 plates, appear to lie on top of one another. These are not the rather expensive originals but copies of a reprint of the plates, published in 1991 by Dover Publications in New York.26 They form a disorderly pile inthe middle of the picture. Underneath this, a white area lies on a wooden colored one, and above this gray, white, and black paintpastes have been poured, pulled, and smeared. In the lower left corner, two white spikes protrude from the white paper and from a black caterpillar out over the blue gray until they intertwine. Apart from a few traces, the colors have retreated between dominantly opposing black and white paint. The plasticity of the paint is supported and recorded by the apparent spatial layers. A bluish triangle of shadows appears to lie on the uppermost book, which requires an explanation.
Since no explanation can be gained from the pictorial arrangement, one can perhaps go back beyond Goethe to the large encyclopedia of optical knowledge by the Jesuit scholar Athanasius Kircher, Ars magna lucis et umbrae, from 1646.27 Like his colleague Franciscus Aguilonius, who published the Opticorum libri sex in Antwerp in 1613, with illustrations by Peter Paul Rubens, Kircher assumed that the three primary colors, red, yellow, and blue, resulted from a threelayered mixing of light and dark. Kircher took over from him the color diagram, which positions the primary colors betweenblack and white, and performed furthermixtures of the primary colors with black and white. The mixing of light and dark into colors is the prerequisite for seeing, as Kirchersays, because indarkness and inpure lightyou cannotsee anything. Goethe discussed Kircher’s work in detail in his theory of color, and particularly emphasized the fact that Kircher had for the first time observed “light, shadows and colour as the elements of seeing.”28 In one of the sections of Kircher that Goethe translated, he wrote: “Because everything that is visible in the world is only visible due to a shadowy light or a light shadow.”29 One could be tempted to apply the old doctrine of the positioning of colors between light and dark, or white and black, and their definition as light shadows, to Pia Fries’s painting tisch dover 1.
- Leon Battista Alberti, On Painting [1435/36], trans. and introduction John R. Spencer, New Haven and London 1966, p. 84; cf. Leon Battista Alberti, Della Pittura – Über die Malkunst [1435/36], ed. and trans. Oskar Bätschmann and Sandra Gianfreda, Darmstadt 2010, pp. 146–47: “Vorrei nella pittura si vedessero tutti i generi e ciascuna sua spezie con molto diletto e grazia a rimirarla.”
- Ibid., p. 85; cf. Alberti, Della Pittura (see note 1), pp. 146–47: “E truovasi certa amicizia de’ colori, che l’uno giunto con l’altro li porge dignità e grazia. Il colore rosato presso al verde e al cilestro si danno onsieme onore e vista.”
- Johann Wolfgang von Goethe, Theory of Colours , Introduction Deane B. Judd, Cambridge, MA 1970, pp. liv–lv; cf. Johann Wolfgang Goethe, Schriften zur Farbenlehre , Zürich/ Stuttgart 1964, pp. 21–22: “Denn es hatte von jeher etwas Gefährliches, von der Farbe zu handeln, dergestalt dass seiner unserer Vorgänger gelegentlich gar zu äussern wagt: Hält man dem Stier ein rotes Tuch vor, so wird er wütend, aber der Philosoph, wenn man nur überhaupt von Farbe spricht, fängt an zu rasen.” Ibid., p. xxxvii: “das Wesen eines Dinges auszudrücken.”
- Ibid.: “Die Farben sind Taten des Lichtes, Taten und Leiden”.
- Charles Blanc, Grammaire des arts du dessin, Paris 1867, p. 22: “Le dessin est le sexe masculin de l’art; la couleur en est le sexe féminin.”
- David Batchelor, Chromophobia, London 2000, p. 22; see also Wolfgang Ullrich, “‘Farben sind oberflächlich’: Vom Verschwinden eines Vorurteils,” Neue Rundschau, no. 113/114, 2002, pp. 23–30, and Ullrich, Wohlstandsphänomene: Eine Beispielsammlung, Hamburg 2010, pp. 107–18.
- Pia Fries interview with Christiane Meyer-Stoll on 12 July 2007, in Sammlung Rolf Ricke: Ein Zeitdokument, exh. cat., Kunstmuseum St. Gallen, Kunstmuseum Liechtenstein, and Museum für Moderne Kunst, Frankfurt am Main, Ostfildern 2008, p. 436; ibid., p. 249: “Meine Malerei handelt direkt von den Kräften des Farbmaterials, das sich selbstredend formt, um sich wieder von Neuem zu verwandeln.”
- Treibhaus 4, exh. cat., Kunstmuseum Düsseldorf 1986, ed. Stephan von Wiese, Düsseldorf 1986, pp. 58–60.
- Interview (see note 8), p. 436; ibid., p: 248: “Transformation von Kraftund Energieströmen, Materialkonsistenz und Fluktuation.”
- See, among numerous others, Theodora Vischer, “Joseph Beuys: ‘thermisch-plastisches Urmeter’ – ein Spätwerk,” in Joseph Beuys –Tagung Basel 1.– 4. Mai 1991, ed. Volker Harlan, Dieter Koepplin, Rudolf Velhagen, Basel 1991, pp. 214–19; and Magdalena Holzhey, Im Labor des Zeichners: Joseph Beuys und die Naturwissenschaft, Berlin 2009.
- Interview (see note 8), p. 436; ibid., p. 249: “In meinen Augen hat die Malerei nicht die Aufgabe zu illustrieren oder abzubilden, sondern Energien freizusetzen und deren Strömen zu folgen.”
- Paul Klee, Beiträge zur bildnerischen Formlehre [1921/22], ed. Jürgen Glaesemer, Basel/Stuttgart 1979, p. 94: “Was heisst überhaupt im Werk Bewegung? Unsere Werke werden sich in der Regel doch nicht bewegen? Wir sind doch keine Automatenfabrik! Nein, unsere Werke werden von sich aus meist ruhig an ihrem Platze bleiben. Und trotzdem sind sie ganz Bewegung” (translation Steve Tomlin).
- Erasmus von Rotterdam, Morias Egkomion sive laus stultitiae, in Ausgewählte Schriften, 8 vols., ed. Werner Welzig, Darmstadt 1995, 2:106–7.: “Wenn einer ein Brett, das mit Rot und Gelb bekleckst ist, entzückt beschaut, weil er glaubt, Apelles oder Zeuxis habe das gemalt, wird der nicht glücklicher sein als einer, der ein Original dieser Künstler teuer erstand, um vielleicht an dem Anblick nicht halb soviel Freude zu haben?”
- Charles Baudelaire, “Die Weltausstellung 1855, III: Eugène Delacroix, ” in Charles Baudelaire: Juvenilia – Kunstkritik 1832–1846, Sämtliche Werke/Briefe in acht Bänden, Friedhelm Kemp and Charles Pichois in cooperation with Wolfgang Drost, vols. 1 and 2, Munich 1977, p. 251 (translation Steve Tomlin); cf. Baudelaire, Curiosités esthétiques, l’art romantique et autres œuvres critiques , Paris 1962, pp. 238–39: “Un bon dessin n’est pas une ligne dure, cruelle, despotique, immobile, enfermant une figure comme une camisole de force; que le dessin doit être comme la nature, vivant et agité […] que la nature nous présente une série infinie de lignes courbes, fuyantes, brisées, suivant une loi de génération impeccable, où le parallelisme est toujours indécis et sinueux, où les concavités et les convexités se correspondent et se poursuivent […].”
- Eugène Delacroix, Art. “touche,” in Dictionnaire des beauxarts, comp. and ed. Anne Larue, Paris 1996, pp. 202–6.
- Baudelaire  1962 (see note 14), p. 61: “que la valeur d’une touche spirituelle, importante et bien placée est énorme,” in Baudelaire 1977, p. 167 (translation Steve Tomlin).
- Monika Wagner, Das Material der Kunst: Eine andere Geschichte der Moderne, Munich 2001, pp. 17–55.
- Ibid., p. 21: “die ästhetische Norm der Transformation des Farbmaterials in eine Farberscheinung.”
- Ibid., “Bedeutungsverlagerung von der Form auf das Material.”
- Heinz Liesbrock, “Ineinander, Auseinander, Zueinander: Farbe und Komposition bei Pia Fries,” in Pia Fries: Malerei 1990–2007, exh. cat., Kunstmuseum Winterthur and Josef Albers Museum Quadrat, Bottrop, Düsseldorf 2007, pp. 101– 6: “eine körperlich betonte Masse […], die durch Gewicht und eine besondere Konsistenz gekennzeichnet ist.”
- Bryan Robertson, Jackson Pollock, London 1960, p. 194.
- See Oskar Bätschmann, “Belebung durch Bewunderung: Pygmalion als Modell der Kunstrezeption,” in Pygmalion: Die Geschichte des Mythos in der abendländischen Kultur, ed. Matthias Mayer and Gerhard Neumann, Freiburg i.Br. 1997, pp. 325–70; and Victor I. Stoichita, The Pygmalion Effect: From Ovid to Hitchcock, Chicago 2008.
- Wassily Kandinsky, Concerning the Spiritual in Art , London 2006, p. 104; cf. Kandinsky, Über das Geistige in der Kunst , Bern 1952, p. 132: “Auf eine geheimnisvolle, rätselhafte, mystische Weise entsteht das wahre Kunstwerk ‚aus dem Künstler’. Von ihm losgelöst bekommt es ein selbständiges Leben, wird zur Persönlichkeit, zu einem selbständigen, geistig atmenden Subjekt, welches auch ein materiell reales Leben führt, welches ein Wesen ist.”
- Maria Sibylla Merian, Insects of Surinam: Metamorphosis Insectorum Surinamensium 1705, Introduction Katharina Schmidt-Loske, Cologne 2009.
- Maria Sibylla Merian, Flowers, Butterflies and Insects: All 154 Engravings from “Erucarum Ortus,” New York 1991.
- Athanasius Kircher, Ars magna lucis et umbrae, Rome 1646, lib. I, pars III.
- Ibid., “Licht, Schatten und Farbe als die Elemente des Sehens.”
- Goethe  1970 (see note 3), pp. 441–46; cf. Goethe, Schriften zur Farbenlehre , pp. 21–22: “Denn alles, was sichtlich in der Welt ist, ist es nur durch ein schattiges Licht oder einen lichten Schatten.”