One reason that historical research is so intriguing is because the facts may be objective and verifiable but the interpretation is subjective, influenced by the perspective of the interpreter.
Even the "facts" themselves might not be a factual as you think. The first rule in research is to use as many primary sources as you can. A primary source is usually defined as a document or other evidence, either contemporary with what you are researching or created by someone involved in the event. The same event, however, is often recorded differently by different eyewitnesses, and an involved individual's perceptions of events can change as time passes.
History is being rewritten all the time. Sometimes it is because new primary sources come to light. More often, it is reinterpretation of an event, which is influenced by the perceptions and biases of the writer. And that's o.k. It doesn't make it right or wrong, as long as verifiable facts aren't changed. New insights may be gained, but that doesn't make the older texts wrong either if they differ.
Whether or not the proclamation issued by Continental Congress in York on November 1, 1777 was the First National Thanksgiving Proclamation is a case in point.
