I think the intention of that line was to show his ignorance!!! Freud's first book was published in 1900, and so his work had been around for a good decade.In 1912 his work was all the rage, and Ismay would have to be deaf, dumb and blind to have missed it. (although many of Freuds theories were not proven until the 1980's) I think the line was also to show Rose in an intelligent light, much like she her love for monet's paintings.
Basically, I think the whole conversation was to show Ismay as an ignorant tycoon who couldn't see past the end of his nose, and Rose as a self educated, but still very young, lady. It was after all, a rather immature joke. I loved it
Correct me if I'm wrong though!!!
Es
xxx