In Królewiec (Königsberg) he started studying theology at a protestant institute. Soon after his parents died and he had to take on jobs. He became a privat teacher in Kowno and then rector in the protestant school in Wilno . He soon returned to Królewiec (Königsberg)wherewhere some books and records got him interested in history.
In 1679 he published a book in Latin about Prussian history and later in German, Alt- und Neues Preussen, as well as Prussian church history (Kirchen-Historia). The works are accompanied by descriptions and illustrations of Prussian people, history and culture as well as copper etching illustrations of cities in Prussia.
His work in the Polish-Lithuanian Commonwealth,Kowno and Wilno awoke his interest in their history as well. He then wrote a comprehensive work on the commonwealth spanning 300 years, the first of its kind.
The Royal Prussian city of Torun/Thorn had become for the most part protestant. In 1677 Hartknoch had been invited to become director at the Torunian Gymnasium. There he worked for ten years. Due to living through years of Tatar attacks and the resulting powerty Christoph Hartknoch's body gave up at age 43 and he died in Torun/Thorn , where he was then burried.
His extensive scientific body of works were a great contribution to the knowledge about Prussia, Pomerania, Samogitia, Courland (Couronia) and Poland.
In his book on Prussian history Hartknoch also features an illustration of the famous Borussus Mathematicus Nicolaus Copernicus, a Landsmann (fellow burgher). Hartknoch wrote: Von den Staedten und Schloessern. Der beruehmte Mathematicus Nicolas Copernicus (About the cities and castles.
The famous mathematician Nicolas Copernicus).
This was written at a late time in Hartknoch's life and at a time when he was director at the Torunian Gymnasium or Educational Institute.Nicolaus Copernicus Portrait