Here we see that the very certainty of having "a building of God, an house not made with hands, eternal in the heavens," makes us groan to possess it. The apostle did not groan in doubt or uncertainty. He did not groan under the weight of guilt or fear. Still less did he groan because he could not satisfy the desires of the flesh or of the mind, or because he could not surround himself with this world's perishable possessions. No; he longed for the heavenly building--the divine, the real, the eternal. He felt the heavy burden of the poor, crumbling tabernacle; it was a grievous hindrance to him. It was the only link with the scene around, and as such it was a heavy clog of which he longed to be rid. But, most clearly, he would not, and could not, have groaned for the heavenly house if he had a single question on his mind with respect to it. Men are never anxious to get rid of the body unless they are sure of possessing something better; nay, they grasp this present life with intense eagerness, and tremble at the thought of the future, which is all darkness and uncertainty to them. They groan at the thought of quitting the body; the apostle groaned because he was in it. This makes all the difference. Scripture never contemplates such a thing as a Christian groaning under sin, guilt, doubt, or fear; or sighing after the riches, honors or pleasures of this vain, sin-stricken world. Alas, alas, they do thus groan through ignorance of their true position in a risen Christ and their proper portion in the heavens! But such is not the ground or character of the groan in the scripture now before us; Paul saw with distinctness his house in the heavens; and, on the other hand, he felt the heavy burden of the tabernacle of clay; and he ardently longed to lay aside the latter and be clothed with the former. Hence, then, there is the fullest harmony between "_we know_" and "_we groan_." If we did not know for a certainty that we have a building of God, we should like to hold our earthly house as long as possible. We see this constantly. Men cling to life. They leave nothing untried to keep body and soul together. They have no certainty as to heaven. They cannot say, "we _know_" that "we _have_" anything there. On the other hand, they have a terrible dread of the future, which to their vision is wrapped up in clouds and thick darkness. They have never committed themselves in calm confidence to God and His word; they have never felt the tranquilizing power of His love. They have viewed Him as an angry Judge instead of seeing Him as the sinner's Friend--a just God and a Saviour--the righteous Justifier. No marvel, therefore, if they shrink with terror from the thought of meeting Him. But it is a totally different thing with a man who knows God as his Father--his Saviour--his best Friend; who knows that Jesus died to save him from his sins, and from all the consequences thereof. Such an one can say: