Is there any information in his letter that he did not actually observe? How do you reconcile this fact with the idea that this is a primary source? Can a document be partially primary and partially secondary

The correct answer to this open question is the following.

Although the question is incomplete because it does not provide a specific reference about the author of the letter or any other reference, we can comment on the following.

A primary source is the piece of information that was written by a character or an individual that lived in the moment of the event, was part of the event, or witnessed the event. This individual could have written a letter, or a document -including a book. Or he/she took a photograph. Or was part of an interview. The secondary source includes information from a third person who was not part of the time or event but has found information through other resources. It is the case of an encyclopedia or researchers/historian books.

the story goes that because of this belief, constantine was able to defeat his foes. constantine became an ardent1 christian. christianity and other religions were tolerated under constantine's rule. constantine also was responsible for the building of a great cathedral in rome.