Task: Question Answering
Input (English): Passage: The origins of the Early Netherlandish school lie in the miniature paintings of the late Gothic period.  This was first seen in manuscript illumination, which after 1380 conveyed new levels of realism, perspective and skill in rendering colour, peaking with the Limbourg brothers and the Netherlandish artist known as Hand G, to whom the most significant leaves of the Turin-Milan Hours are usually attributed. Although his identity has not been definitively established, Hand G, who contributed c. 1420, is thought to have been either Jan van Eyck or his brother Hubert. According to Georges Hulin de Loo, Hand G's contributions to the Turin-Milan Hours "constitute the most marvelous group of paintings that have ever decorated any book, and, for their period, the most astounding work known to the history of art".Jan van Eyck's use of oil as a medium was a significant development, allowing artists far greater manipulation of paint. The 16th-century art historian Giorgio Vasari claimed van Eyck invented the use of oil paint; a claim that, while exaggerated, indicates the extent to which van Eyck helped disseminate the technique. Van Eyck employed a new level of virtuosity, mainly from taking advantage of the fact that oil dries so slowly; this gave him more time and more scope for blending and mixing layers of different pigments, and his technique was quickly adopted and refined by both Robert Campin and Rogier van der Weyden. These three artists are considered the first rank and most influential of the early generation of Early Netherlandish painters. Their influence was felt across northern Europe, from Bohemia and Poland in the east to Austria and Swabia in the south. 
Question: What is the first name of the person who employed a new level of virtuosity, mainly from taking advantage of the fact that oil dries so slowly?
Output (English): Jan.