In a note (on Facebook, no less) legendary anchor and longtime newsman Dan Rather voiced concern about the social network's "mysterious algorithms" while heralding its potential as a "tremendous force for good."

In his nearly 500-word post, Rather cites Facebook as among the "literally world changing" social networks that are "reimagining my chosen line of work and all of your access to news."

And yet, I also worry about the opaqueness of Facebook and its mysterious algorithms. My team and I try to figure out why some posts seem to "hit" and are shared thousands of times while reaching millions of people, while others fare much more modestly. And I recognize that I am not doing the kind of reporting that requires budgets for travel or an extensive staff.

Rather notes that his career was "supported by large and vibrant news organizations," part of a journalism community that has been shaken by "unprecedented disruptive forces of the internet."

On balance, I feel that all this change is a tremendous force for good. As this article states, I believe Facebook never set out to become the primary means of journalistic communication. We have to figure out how to make that work best for all concerned.

In his post, Rather linked to a story by Columbia Journalism Review titled "Facebook is eating the world" which examines how the social network has supplanted other institutions and platforms as the primary means of news distribution.

Rather isn't alone among journalists that have voiced concern over Facebook's lack of openness. For years, as Facebook has consolidated its power to direct the attention of its 1.13 billion daily users, the media world has called on Facebook to be more transparent about the forces driving its proprietary News Feed.

In June, Facebook gave users — and journalists — a vague road map of sorts to navigating its algorithmically driven News Feed with a blog post called "News Feed values." In that post, Facebook said informativeness is a key component of its News Feed.