Well, my mentioning that Parent knows Picasso, we've already made one assumption. I merely took a step further to use a similar example to stay on theme. It's the opposite assumption that the parent knows nothing of Picasso, or would give the wrong information. Assumptions are all over the place in both examples, wouldn't you say? You need assumptions for these sorts of theoretical discussions.
Yes, but aren't we lucky people didn't take that as fact over the centuries? If they'd accepted that libraries weren't for the masses, I doubt we'd even be having this conversation.
And I'm saying that people with feelings and opinions interpret the facts for others. Facts exist, but it's what we do with them that creates history. If people didn't interpret the facts for others, every individual would have to travel to every cave in every country to discover first hand the facts, because even reading about it in books is colored by the writer's personal experience.
I absolutely agree that a history book is more valuable than the Daily Prophet, but even the best history book has the author's bias in what they write about from which viewpoint. The best writers, like Batty, cover almost everything, but even she'll admit there are some subjects on which she is not the definitive authority, and will reference various other source material.