When the Danzig merchant, Johan Pyre, died in 1455, he left a merchant's book in which he had entered extensive data and details about his 35-year business activity. The book is one of the Hanseatic merchant books and bears witness to the diverse facets of Hanseatic trade in a politically turbulent and tense time. Although this oldest Gdańsk merchant book is occasionally cited in research literature, it has not been adequately researched so far. Anna Paulina Orlowska now takes on this desideratum in her present, two-volume work. It deals with Pyre's biographical data, his bookkeeping, payment methods, trade routes, goods, business partners and much more. Volume 2 contains the critical edition of the Kaufmannsbuch.