Shoes are a woman's best friend??

That is not exactly surprising news but I had always thought that Diamonds were a woman's best friend. With Diamonds I can understand it; it is the shiny glitter and the value/rarity of it that makes it so indispensable to a woman.
But shoes? I have seen movies where a woman goes out to buy shoes so as to forget her problems. How does that work?
How on earth does buying shoes solve ones problem? Or for that matter, why are the shoes so important to a woman?
I wonder what the cavewomen did to solve their problems. I guess that there is a grain of truth in the saying that 'Men are from Mars and Women from Venus'.