the word obvious comes from ob + via, in other words something blocking the path (to understanding)
Are you sure it meant blocking understanding? I thought it was more like "in front of you", as in "you can't miss it".
According to http://www.etymonline.com/index.php?search=obvious, the original meaning was "commonplace", i.e. something you're likely to encounter along the way, and the modern meaning "evident" doesn't appear until the 1630s.