Good question. There are many metrics I can think of to measure a great scholar/author or a business/political leader.
How about a College alumnus makes those lists:
http://www.biography.com/people/groups/famous-alumni-of-university-of-chicago - by biography standard
https://en.wikipedia.org/wiki/List_of_University_of_Chicago_alumni - by Wiki standard
http://www.uchicago.edu/about/accolades/ - by UChicago standard
Here we are talking about the most accomplished College alumni so the bar is high.
Both Bernie Sanders and Susan Sontag would qualify.