I need resources regarding the history & meaning of a PhD I am taking over the position of program director for a relatively new PhD program, at a college which has only one PhD program (mine).

The students are generally mid-career public health types, all are post-masters. 

I'd like to expose them to something about the "meaning' of the PhD, its history, roots, something like that.... I remember in my program we got a lecture about the monks in medieval times, protecting knowledge and books, something like that. It had quite an impact on me at the time (long ago now). 

Does anyone have any ideas about a resource, perhaps readings or other media, that I could assign to them which might instill this same value?
You can see, breif history of PhD and a series of paper in Nature, Nature 1, Nature 2, and Nature 3. 

Also, this paper is helpful, Changing PhD.