One basic assumption behind the Declaration of Independence, for example, is that the King of England had certain responsibilities toward his subjects, and that they had the right to complain if he neglected those responsibilities. These questions relate to interpreting documents. If you know who wrote a document, who was supposed to read it, why it was written, and some of the basic assumptions behind it, you can begin to judge whether its contents are reliable. A letter complaining about unfair taxation might not be a reliable source about tax levels. This question can be answered in many ways, depending on the questions which interest you.
Documents reveal much more about a society than their authors intend.
Every document communicates something. As you read, you should ask yourself what it means to you. Even tax records can interest historians because they provide evidence for an argument. Many of the documents we will read in this course have much greater intrinsic interest, but their ultimate value to you is a matter only you can decide.