On the same day Luther spoke admirably about the future eternal life and its unspeakable joy: “Human reason can’t grasp it by speculation. With our thoughts we can’t get beyond the visible and physical. No man’s heart comprehends eternity. One might suppose that according to the saying, ‘Even pleasure becomes burdensome,’ one would get tired of eternity. What pleasure is like in eternity we can’t imagine. Isaiah said, ‘Be glad and rejoice forever in that which I create’ [Isa. 65:18].” (Luther’s Works, v. 54, p.325)