A document is more than just the text intended to relay specific information. It can also reveal something about the author and his or her intentions, and about the reader for whom the text was written. The date the document was created can be related to other documents or events. How the document was handled by third parties may explain why it has been preserved.
Using the example of this letter from Reinhard Heydrich to Martin Luther, dated 26 February 1942, we show here how a document can be read as a historical source.
