After disagreeing with the first two items on Parisian Chic's (Parisian Chic: A Style Guide by Ines de la Fressange ) list of seven essential items, #3 is a definite yes. Especially when it looks like this:
The irony is, the only sweater I've found to have a kind of classic simplicity is this one from J. Crew. It would have been nice to list more choices (perhaps there is a store in Paris that only sells navy cashmere sweaters??) but as with love and the perfect mascara, when it's right, you only need one.