I am talking about works of art or science that have been commented on so extensively, that more people know about the works from their commentary rather than from reading the source material.
Lets use the example of Freud, where his work was highly influential but now widely discredited. If someone wanted a better understanding of psychology, should they read Freud?
What about when something isn’t discredited, was highly influential, but has been used as a building block for newer, more compressive theories. Like “The Wealth of Nations” by Adam Smith. If most modern books on economics will summarize the principles in “Wealth of Nations,” then how much value is there in reading the source material?
Religion, obviously, but that’s neither art nor science.
I’d say the point at which you should read the original material is that point when you are about to use that material as supporting material for your work, or to discredit/disprove someone else’s.
Well, why do they want a better understanding of psychology? If they don’t have any special reason to read Freud’s books but just want to know more about the history of psychology then they’re probably better off spending their time reading a book like Morton Hunt’s The Story of Psychology. (Which I’ve never read myself so I can’t personally recommend it, I picked it because it seems to be a well-regarded general history of psych book.)