I was talking with a student of mine about Goldbach's conjecture, and a certain point he asked why this apparently simple statement is so difficult to prove.
Half-joking, I answered "well, because prime numbers are made to be multiplied, not added", explaining that it is a well-known quote by Lev Landau, or at least this is what a Google research shows (see for instance here).
However, I was unable to find any authoritative source supporting this attribution. This led me to ask what follows:
Q. Is this quote really by Landau? If so, what is the original source? Is it written in some of his papers, or is there some historical account supporting this credit?