And the LORD went before them by day in a pillar of cloud to lead them along the way, and by night in a pillar of fire to give them light, that they might travel by day and by night.
Now that God's people have been driven away from Egypt by Pharaoh, they are heading into the wilderness, following Moses, who speaks to them from God. God also provides a guide by his presence in the form of a pillar of fire at night and a pillar of cloud during the day.
Can you imagine how amazing this would have been for those following? They had a visible representation of the presence of God right before them! How they must have been on their best behaviour, with their God come down to reside with them for a time...
Even with God so obviously with them, delivering them from their oppressors and returning them to the land promised to their fore-fathers, the people of Israel would still rebel against their God. This is further evidence that signs and wonders do not lead people to believe. God must open their eyes and ears in a spiritual way so that they can see his glory and get a sense of his nature enough to forget their old ways and follow him.