"an artist has got to get acquainted with himself 

just as much as he can. 

It is no easy job 

as it is not a present-day habit of humanity"

From  My Name is Asher Lev by Chaim Potok

Rembrandt gets the prize for the most (62) self portraits.  

(the ancient equivalent of a selfie.)

But he also painted 600 paintings (plus drawings and etchings)