Just as the disciples on the road to Emmaus recognized Jesus in the breaking of the bread, so we, through the working of the Holy Spirit, recognize our Lord in the Word and Sacraments.
We worry about the fact our days are as grass – so we try to scratch out a place for ourselves, to make a permanent, lasting place, to climb to higher places and succeed, more often than not, only to hurt each other in the process.
The point Luther made, again and again, was that distance between God and sinners is collapsed when the crucified Christ himself comes to sinners through a preacher.