Geometries of Light and Shadows, from Piero della Francesca to James Turrell

This chapter addresses the problem of representing light and shadow in the artistic culture, from its uncertain beginnings, related to the studies on conical linear perspective in the Fifteenth Century, to the applications of light projection in the installations of contemporary art. Here are examined in particular two works by two artists, representing two different conceptual approaches to the perception and symbolism of light and shadow. The first is the so-called Brera Madonna by Piero della Francesca, where the image projected from a luminous radiation is employed with a narrative purpose, supporting the apparently hidden script of the painting and according to the artist\u2019s own speculations about perspective as a means to clarify the phenomenal world. The second is one of James Turrell\u2019s Dark Spaces installations, where quantum electrodynamics interpretation of light is taken into account: for Turrell, light is physical and thus can shape spaces where the visitors, or viewers, can \u201csee themselves seeing.\u201d In his body of work, perceptual deceptions are carefullyproduced by the interaction of the senses with his phenomenal staging of light and darkness, but a strong symbolic component is always present, often related to his own speculative interests. In both cases, light and shadow, through their geometries, emphasize both phenomenal and spiritual contents of the work of art, intended as a device to expand the perception and the knowledge of the viewer

L'Esthétique de Lamennais

Rodis Lewis Genevieve. L'Esthétique de Lamennais. In: Annales de Bretagne. Tome 62, numéro 1, 1955. pp. 33-61

Quelques remarques sur la question de la vitesse de la lumière chez Descartes/Some comments about the question of the speed of light in Descartes's works

SUMMARY. — In Descartes Le Monde ou traité de la lumière, light is transmitted instantaneously. Moreover, Descartes's letter to Isaac Beeckman dated 22 August 1634 makes the whole of Cartesian philosophy depend on the instantaneous transmission of light. In the 5th part of Descartes's Discours de la Méthode, sunlight traverses the immense heavens « in an instant », which is illustrated in Descartes's Dioptrique by the blind man's stick, whose two ends are moved together. However, the Latin translation of the Discours and of the first two essays, joined in 1644 to Descartes's Principia philosophiae, reads « temporis momento ». From 1638 onwards, Descartes's letters to Morin and to Mersenne specify that light is not a motion but an action with an « infinite speed » (26 October). The Principes repeat « conatus », « effort » (III, art. 55, 59, which read : « quamdiu durat ») and « temporis momento » (art. 57, 63, 64). In 1647, the translator of article 59 added that « the speed » produced « becomes rather large in a short time », and he described the « effort », which goes « a little faster in the second instant », he wrote, than it does in the «first instant ». And « this effort continues as long as the circular motion lasts »... Descartes was the first who wanted to observe the interval of this transmission of light at the time of an eclipse, but the moon was too close...RÉSUMÉ. — Dans Le Monde ou traité de la lumière, la transmission de celle-ci est instantanée ; et la lettre à Beeckman du 22 août 1634 y subordonne toute la philosophie cartésienne. En la 5e partie du Discours de la Méthode, la lumière du soleil traverse « en un instant » l'immensité des cieux, ce que la Dioptrique illustre par le bâton de l'aveugle dont les deux bouts sont mus ensemble. Mais la traduction latine du Discours et des deux premiers Essais, jointe en 1644 aux Principia philosophiae, dit : « temporis momento ». Dès 1638, des lettres à Morin et à Mersenne précisent que la lumière n'est pas un mouvement, mais une action avec une « vitesse infinie » (26 octobre). Les Principes répètent « conatus », « effort » (III, art. 55, 59 disant : « quamdiu durat ») et « temporis momento » (art. 57, 63, 64). En 1647, la traduction de l'article 59 ajoute que « la vitesse » causée « devient en peu de temps assez grande », et décrit l'« effort » qui, du « premier instant » passe « un peu plus vite au second ». Et « cet effort continue autant que dure le mouvement circulaire »... Descartes est le premier qui ait voulu observer le décalage de cette transmission lors d'une éclipse, mais la lune était trop proche...Rodis Lewis Genevieve. Quelques remarques sur la question de la vitesse de la lumière chez Descartes/Some comments about the question of the speed of light in Descartes's works. In: Revue d'histoire des sciences, tome 51, n°2-3, 1998. « Pour Descartes » Mathématiques et physique cartésiennes. pp. 347-354

Platon, les Muses et le Beau

Rodis Lewis Genevieve. Platon, les Muses et le Beau. In: Bulletin de l'Association Guillaume Budé, n°3, octobre 1983. pp. 265-276