Josh 5:15

“And in what manner is Jericho holy ground since it is retained by the enemies? This indicates, and not by accident, that the chief of the army of the power of the Lord sanctifies every place to which he comes, for Jericho itself was not a holy place. But because the chief of the army of God came there, the place is said to be holy. I also dare something more and say that even the place where Moses stood was not holy through Moses himself but because the Lord stood with him. The presence of the Lord had sanctified the place; and on that account, it is said to him, "Loosen the latchet of your sandal; for the place on which you stand is holy ground."”

“Now, grasp the mystical meaning of Holy Writ. As long as we are walking through the wilderness, it is necessary that we wear sandals to cover and protect our feet, but when we shall have entered the Land of Promise, we shall hear with Jesus [Joshua], the son of Nave [Nun]: "Remove your sandals from your feet, for the place upon which you are standing is holy." When, therefore, we enter into the kingdom of heaven, we shall have no need of sandals or for protection against this world, but—to give you a new thought—we shall follow the Lamb that has been slain for us.”