Question: Who is the sibling of the painter who was an early champion of oil as a medium in painting?

full_context: Document 1: Late Middle Ages: The changes brought about by these developments have led many scholars to view this period as the end of the Middle Ages and beginning of modern history and early modern Europe. However, the division is somewhat artificial, since ancient learning was never entirely absent from European society. As a result there was developmental continuity between the ancient age (via classical antiquity) and the modern age. Some historians, particularly in Italy, prefer not to speak of the late Middle Ages at all, but rather see the high period of the Middle Ages transitioning to the Renaissance and the modern era.
Document 2: St. Anthony Beaten by Devils: This tryptch is missing a panel, lost when it was disassembled in 1777, but the panel with "St. Anthony Beaten by Devils" is currently on display at the Pinacoteca Nazionale. The painting depicts St. Anthony being clubbed by three devils who have surrounded him. According to stories, St. Anthony led a monastic life, and was tempted and tortured by devils as a test of faith.
Document 3: Virgin and Child with Canon van der Paele: The Virgin and Child with Canon van der Paele is a large oil-on-oak panel painting completed around 1434–36 by the Early Netherlandish painter Jan van Eyck. It shows the painting's donor, Joris van der Paele, within an apparition of saints. The Virgin Mary is enthroned at the centre of the semicircular space, which most likely represents a church interior, with the Christ Child on her lap. St. Donatian stands to her right, Saint George — the donor's name saint — to her left. The panel was commissioned by van der Paele as an altarpiece. He was then a wealthy clergyman from Bruges, but elderly and gravely ill, and intended the work as his memorial.
Document 4: Late Middle Ages: Modern historiography on the period has reached a consensus between the two extremes of innovation and crisis. It is now generally acknowledged that conditions were vastly different north and south of the Alps, and the term ``Late Middle Ages ''is often avoided entirely within Italian historiography. The term`` Renaissance'' is still considered useful for describing certain intellectual, cultural, or artistic developments, but not as the defining feature of an entire European historical epoch. The period from the early 14th century up until -- and sometimes including -- the 16th century, is rather seen as characterized by other trends: demographic and economic decline followed by recovery, the end of western religious unity and the subsequent emergence of the nation state, and the expansion of European influence onto the rest of the world.
Document 5: Late Middle Ages: The ideas of the Italian Renaissance were slow to cross the Alps into northern Europe, but important artistic innovations were made also in the Low Countries. Though not – as previously believed – the inventor of oil painting, Jan van Eyck was a champion of the new medium, and used it to create works of great realism and minute detail. The two cultures influenced each other and learned from each other, but painting in the Netherlands remained more focused on textures and surfaces than the idealized compositions of Italy.
Document 6: History of science: The renewal of learning in Europe, that began with 12th century Scholasticism, came to an end about the time of the Black Death, and the initial period of the subsequent Italian Renaissance is sometimes seen as a lull in scientific activity. The Northern Renaissance, on the other hand, showed a decisive shift in focus from Aristoteleian natural philosophy to chemistry and the biological sciences (botany, anatomy, and medicine). Thus modern science in Europe was resumed in a period of great upheaval: the Protestant Reformation and Catholic Counter-Reformation; the discovery of the Americas by Christopher Columbus; the Fall of Constantinople; but also the re-discovery of Aristotle during the Scholastic period presaged large social and political changes. Thus, a suitable environment was created in which it became possible to question scientific doctrine, in much the same way that Martin Luther and John Calvin questioned religious doctrine. The works of Ptolemy (astronomy) and Galen (medicine) were found not always to match everyday observations. Work by Vesalius on human cadavers found problems with the Galenic view of anatomy.
Document 7: Oil paint: As public preference for naturalism increased, the quick - drying tempera paints became insufficient to achieve the very detailed and precise effects that oil could achieve. The Early Netherlandish painting of the 15th century saw the rise of the panel painting purely in oils, or oil painting, or works combining tempera and oil painting, and by the 16th century easel painting in pure oils had become the norm, using much the same techniques and materials found today. The claim by Vasari that Jan van Eyck ``invented ''oil painting is not correct but has cast a long shadow, but van Eyck's use of oil paint achieved novel results in terms of precise detail and mixing colours wet - on - wet with a skill hardly equalled since. Van Eyck's mixture may have consisted of piled glass, calcined bones, and mineral pigments boiled in linseed oil until they reached a viscous state -- or he may have simply used sun - thickened oils (slightly oxidized by Sun exposure). He left no written documentation.
Document 8: Portrait of a Man with a Blue Chaperon: Portrait of a Man with a Blue Chaperon (or Portrait of a Man with a Blue Hood, earlier Portrait of a Jeweler or Man with a Ring) is a very small (22.5 cm x 16.6 cm with frame) oil on panel portrait of an unidentified man attributed to the Early Netherlandish painter Jan van Eyck.
Document 9: The Judgement of Cambyses: The Judgement of Cambyses is an oil on wood diptych by Dutch artist Gerard David, depicting the arrest and flaying of the corrupt Persian judge Sisamnes on the order of Cambyses, based on Herodotus' "Histories". The diptych was commissioned in 1487/1488 by the municipal authorities of Bruges which requested a series of panels for the deputy burgomaster's room in the town hall.
Document 10: Late Middle Ages: Modern historiography on the period has reached a consensus between the two extremes of innovation and crisis. It is now (generally) acknowledged that conditions were vastly different north and south of the Alps, and "Late Middle Ages" is often avoided entirely within Italian historiography. The term "Renaissance" is still considered useful for describing certain intellectual, cultural, or artistic developments, but not as the defining feature of an entire European historical epoch. The period from the early 14th century up until – and sometimes including – the 16th century, is rather seen as characterised by other trends: demographic and economic decline followed by recovery, the end of western religious unity and the subsequent emergence of the nation state, and the expansion of European influence onto the rest of the world.
Document 11: Crucifixion and Last Judgement diptych: The Crucifixion and Last Judgement diptych (or Diptych with Calvary and Last Judgement) consists of two small painted panels attributed to the Early Netherlandish artist Jan van Eyck, with areas finished by unidentified followers or members of his workshop. This diptych is one of the early Northern Renaissance oil on panel masterpieces, renowned for its unusually complex and highly detailed iconography, and for the technical skill evident in its completion. It was executed in a miniature format; the panels are just high by wide. The diptych was probably commissioned for private devotion.
Document 12: Annunciation (van Eyck, Washington): The Annunciation is an oil painting by the Early Netherlandish master Jan van Eyck, from around 1434–1436. The panel is housed in the National Gallery of Art, in Washington D.C. It was originally on panel but has been transferred to canvas. It is thought that it was the left (inner) wing of a triptych; there has been no sighting of the other wings since before 1817. The annunciation is a highly complex work, whose iconography is still debated by art historians.
Document 13: The Just Judges: The Just Judges or The Righteous Judges is the lower left panel of the "Ghent Altarpiece", painted by Jan van Eyck or his brother Hubert Van Eyck between 1430–32. It is believed that the panel shows portraits of several contemporary figures such as Philip the Good, and possibly the artists Hubert and Jan van Eyck themselves. The panel was stolen in 1934 and has never been found.
Document 14: Late Middle Ages: The period saw several important technical innovations, like the principle of linear perspective found in the work of Masaccio, and later described by Brunelleschi. Greater realism was also achieved through the scientific study of anatomy, championed by artists like Donatello. This can be seen particularly well in his sculptures, inspired by the study of classical models. As the centre of the movement shifted to Rome, the period culminated in the High Renaissance masters da Vinci, Michelangelo and Raphael.
Document 15: Humanism: Better acquaintance with Greek and Roman technical writings also influenced the development of European science (see the history of science in the Renaissance). This was despite what A. C. Crombie (viewing the Renaissance in the 19th-century manner as a chapter in the heroic March of Progress) calls "a backwards-looking admiration for antiquity", in which Platonism stood in opposition to the Aristotelian concentration on the observable properties of the physical world. But Renaissance humanists, who considered themselves as restoring the glory and nobility of antiquity, had no interest in scientific innovation. However, by the mid-to-late 16th century, even the universities, though still dominated by Scholasticism, began to demand that Aristotle be read in accurate texts edited according to the principles of Renaissance philology, thus setting the stage for Galileo's quarrels with the outmoded habits of Scholasticism.
ground_truth: Hubert Van Eyck
sub_queries: What painter was an early champion of oil as a medium in painting? Answer: Jan van Eyck
Jan van Eyck >> sibling Answer: Hubert Van Eyck