An older Cabernet Sauvignon should be decanted carefully—and not always for the same reason as a young wine. With mature bottles, the principal purpose is usually to separate the clear wine from sediment while limiting unnecessary exposure to oxygen. Stand the bottle upright in advance, open it gently, and pour slowly into a clean decanter while watching the neck for sediment. Very old or fragile wines may be better served shortly after opening rather than left in a decanter for hours.