The original French text of the book “Discours de la méthode pour bien conduire sa raison, et chercher la verité dans les sciences” authored by René Descartes is/are in the public domain and not protected by copyright because at least 100 years (viz. 376) have passed since the author’s death in 1650.

The German translation of the book “Discours de la méthode pour bien conduire sa raison, et chercher la verité dans les sciences” (“Abhandlung über die Methode, richtig zu denken und Wahrheit in den Wissenschaften zu suchen”) authored by Julius Hermann von Kirchmann is/are in the public domain and not protected by copyright because at least 100 years (viz. 142) have passed since the author’s death in 1884.