1 Samuel 6:19
The Ark of the Covenant was captured and taken by the Philistines. After some judgments had fallen on the heathen cities because of it, the Ark was put on a cart and sent back.

......The cattle pulled the cart off the road into a field. When some of the people saw the Ark the news spread. Thousands came curious to see it.

..........The cover was thrown off and the people saw it for the first time.

................Suddenly a plague struck them and fifty thousand fell dead.

It showed that no one can come to God except through a High Priest or sacrifice. Man cannot come into God's presence univited. He needs a Mediator.