Matthäus Prätorius was a Protestant pastor, later a Roman Catholic priest, a historian and ethnographer.

He probably grew up speaking both German language

German language

German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

 and Lithuanian language

Lithuanian language

Lithuanian is the official state language of Lithuania and is recognized as one of the official languages of the European Union. There are about 2.96 million native Lithuanian speakers in Lithuania and about 170,000 abroad. Lithuanian is a Baltic language, closely related to Latvian, although they...

, which helped him when preaching to the ethnic Lithuanians

Prussian Lithuanians

The term Prussian Lithuanians or Lietuvininkai refers to a Western Lithuanian ethnic group, which did not form a nation and inhabited a territory in East Prussia called Prussian Lithuania or Lithuania Minor in contrast to the Grand Duchy of Lithuania and later the Republic of Lithuania .Unlike most...

 in Ducal Prussia

Ducal Prussia

The Duchy of Prussia or Ducal Prussia was a duchy in the eastern part of Prussia from 1525–1701. It was the first Protestant duchy with a dominant German-speaking population, as well as Polish and Lithuanian minorities...

. His work about Prussia and its culture, Deliciae Prussicae oder Preussische Schaubühne, resembles the work of Christoph Hartknoch

Christoph Hartknoch

Christoph Hartknoch was a Prussian historian and educator.- Biography :Hartknoch was born in Jablonken near Ortelsburg in the Duchy of Prussia. His father, Stephan Hartknoch of Lyck , is recorded to have been married for 100 years and to have lived to the age of 130...

, with whom he collaborated. Prätorius' work provides much more ethnographic information regarding local Lithuanians and Old Prussians

Old Prussians

The Old Prussians or Baltic Prussians were an ethnic group, autochthonous Baltic tribes that inhabited Prussia, the lands of the southeastern Baltic Sea in the area around the Vistula and Curonian Lagoons...

. It was only published partially, in 1871. A complete edition, in seven volumes, with original German text and Lithuanian translation, is under preparation in Lithuania.

In 1701, having converted from Protestantism

Protestantism

Protestantism is one of the three major groupings within Christianity. It is a movement that began in Germany in the early 16th century as a reaction against medieval Roman Catholic doctrines and practices, especially in regards to salvation, justification, and ecclesiology.The doctrines of the...

 to Roman Catholicism, he appealed against an ongoing case of witch-hunt

Witch-hunt

A witch-hunt is a search for witches or evidence of witchcraft, often involving moral panic, mass hysteria and lynching, but in historical instances also legally sanctioned and involving official witchcraft trials...

.