The creator of a work has unique rights over that work. There are literally authorities on created works. They are the "authors." I think what Sagan is getting

The creator of a work has unique rights over that work. There are literally authorities on created works. They are the "authors." I think what Sagan is getting at is that no such relationship between scientists and science exists. Although the author of a scientific paper can be an authority on it, that authority doesn't extend to the subject of the paper.