This past semester, I was a tutor for the required methodology course in the history department. My students were all sophomores and juniors hoping to concentrate in history (pending their ability to pass this course, which, happily, they all did).
Over the course of the semester, one of the main topics of discussion in section was the responsible use of sources. They all wrote papers based on a common collection of primary sources, then read and reviewed each others' work, so we had ample opportunity to see how different people used the same sources to support completely different (and often contradictory) arguments. For the most part, these arguments were reasonable and faithful to the sources.
Several students had some difficulty accepting the idea that the same sources could be interpreted in such diverse ways. They wanted to know what happened, not what some historian decided had happened, and it was my job to break the bad news to them that histories are the stories we tell ourselves about the past, not revelations. Two students found this particularly hard to take and found themselves standing on the brink of a sort of nihilistic postmodernism — you can make up anything and call it history!
Of course, I did my best to talk them back from the edge of despair, pointing out that this was the whole point of basing arguments on primary evidence. It's true that you can make sources say pretty much anything, but it is the historian's responsibility to interpret the sources in a way that represents them faithfully and makes a brave attempt to arrive at some sort of good-faith understanding about the past.
One of the tools I used during discussion was this spoof trailer for Shining, a feel-good family movie about "a writer looking for inspiration" and "a kid looking for a dad." I think it helped clarify what I was trying to say about the malleability of sources and the importance of responsible quotation: