Charles Spurgeon Commentary Jeremiah 9:12

"Who is the wise man, that may understand this? and [who is] he to whom the mouth of Jehovah hath spoken, that he may declare it? wherefore is the land perished and burned up like a wilderness, so that none passeth through?" — Jeremiah 9:12 (ASV)

The land would never have been desolate if it had not been for the wickedness of the people. Sin—sin it is that causes the ruin.

There are some who quibble about the punishment that God imposes on sin; they would do better if they found fault with the sin which brings its own punishment with it. There is nothing arbitrary in God's justice; he allows sin itself to ripen, and when it is finished, it brings forth death eternal.