I am a BIG fan of A Foreign Affair - Jean Arthur's portrayal was just fantastic. Her seemingly automatic ability to play a comedic, stiff and unbending character is without a doubt unparalleled. Mr Wilder could not have found a more perfect person for her part!
I must say, in my opinion, Marlene acted rings around Jean Arthur. The qualities she brought to her character, Ericka, had far more depth. It was an awkward juxtaposition: one a clown and and the other, a survivor.
