He writes, "Metaphysics has as the proper object of its enquiries three ideas only: God, freedom, and immortality-so related that the second concept when combined with the first, should lead to the third as a necessary conclusion." Kant believes that our goal in life is to strive for the perfect good of happiness proportional to virtue. He says we have to continue to strive for this goal which would not last long with the death of our mortal body. "This infinite progress is possible, however, only under the presupposition of an infinitely enduring existence and personality of the same rational being; this is called the immortality of the soul."