"Caviar is to dining what a sable coat is to a girl in evening dress"

This quote by Ludwig Bemelmans is a contrast between two apparently unrelated products. Caviar is a type of costly fish eggs that is frequently worked as a special at formal suppers. A sable coat is a luxurious fur coat that is often worn by ladies to official events. Bemelmans is recommending that caviar is to dining what a sable coat is to a lady in evening dress. To put it simply, caviar is an elegant and costly product that is typically served at official dinners, simply as a sable coat is an elegant and expensive item that is typically used by ladies to formal occasions. Both items are related to luxury and elegance, and they both add a touch of sophistication to the event. This quote is a suggestion that even the smallest details can make a big distinction in the total atmosphere of an occasion.