Pope St John Paul II professed that if the Church failed to teach constantly the truths concerning the last things (death, judgment, Heaven, and Hell), she would gravely mutilate the Gospel received from Our Lord Jesus Christ. This little book seeks to avoid such a mutilation. Written three centuries ago it has lost nothing of its relevance today, for the simple reason that in every generation the ultimate meaning of life is discovered only in the light of eternity. Indeed, the best way to live a happy life is to keep your eyes fixed on eternity, and a good life makes for a peaceful and happy death.