There are many moral standings and ideals that existed in the last that are completely at odds with what we think today. Or there were ideas on face and science that are just completely strange in comparison with today's ideas. Primary resources don't show a complete picture, because there are always gaps that need to be filled along the way. For example, a lot of primary sources and writing for Viking cultures were written by Christian writers, so it doesn't offered a clear perspective on the pagan side.
