I am currently reading a wonderfully enlightening book titled "Witness In Our Time" by Ken Light. The Eugene Richard's quote below is from this great read. Here a photo teaching link with more about the book, highly recommended to all photographers especially those interested in photojournalism.
http://aphototeacher.com/2008/02/06/witness-in-our-time-working-lives-of-documentary-photographers/
http://aphototeacher.com/2008/02/06/witness-in-our-time-working-lives-of-documentary-photographers/