The most gifted and idiosyncratic painter in Cologne around 1500 was also the city's most enigmatic figure. To this day, there is no agreement about his origin, and recently it has even been posited that he may have exported his panels and altars from the Netherlands to the city on the Rhine. His painting is deeply permeated by early Netherlandish realism, yet in its colouring and fondness for decorative elements owes a great deal to the Cologne tradition. There appears to be an especially close connection to the art of Stefan Lochner, one that even extends to the workshop practice of unusually detailed underdrawing utilising dense cross-hatching. For that reason, it seems more likely that his three monumental altars for Cologne were produced in the city. The work after which he is named, the 'St Bartholomew Altar', now in Munich's Alte Pinakothek, was commissioned for his monastery by a Carthusian, seen kneeling before the saint. The 'Crucifixion Altar' and 'St Thomas Altar', both in Cologne's Wallraf-Richartz-Museum, were commissioned by the jurist Dr. Peter Rjnck, who was also closely associated with the charterhouse. Whereas these major commissions likely date from the last decade of the fifteenth century, an early work by the "St Bartholomew Master" is preserved in the form of the book of hours of Sophia van Bylant, also in the Wallraf-Richartz-Museum. The manuscript contains miniatures by the master, one of which bears the date 1475.