Some people dream of having a swimming pool at home, while those who have one hardly ever use it. Those who have lost a loved one feel a profound sense of loss, while others often complain about their living relatives. Those without a partner long for one, while those who have one often don't appreciate it. The hungry would give anything for a meal, while the satiated complain about the taste of their food. Those without a car dream of owning one, while those who have a car are always looking for a better one.