Question: I noticed in the book "A Beautiful Mind", by Sylvia Nasar, that a recommendation letter, for PhD applications, written for John F. Nash runs as follows: *This man is a genius.*

Then, out of curiosity, I wonder that if such reference letters for PhD applications work in the present days? 

Image taken from the [Graduate Alumni Records](http://findingaids.princeton.edu/collections/AC105/c3) of Princeton University:

[![enter image description here](https://i.stack.imgur.com/p7gtk.jpg)](https://i.stack.imgur.com/p7gtk.jpg)

Answer: 
Even though the event that inspired this questions may or may not have actually happened, the question is still a valid one. 

I suspect it greatly depends on who wrote the recommendation. If the person writing that recommendation is a great authority in this field and is known for not giving praise easily, then such a recommendation letter might help. On the other hand, if I were to write such a letter...
A letter that simply states "This man is a genius" is not helpful for judging the likelihood of a PhD applicant being successful since it takes a lot more than genius to succeed at a PhD and genius is not a requirement for success. Further, the skills required to become "academically famous" do not necessarily make you better at judging the abilities of others. Academically famous people many see more good students than others, but that is not enough for me to take their word at face value, I want to see evidence of why the recommender thinks the person is a genius. Finally, if the student is so good that nothing more needs to be said about, I would be worried about why an academically famous person would be unable to convince his department to accept the genius and convince the genius to attend.