And the LORD went before them by day in a pillar of a cloud, to lead them in the way; and by night in a pillar of fire, to give them light; to go by day and night:
All Commentaries on Exodus 13:21 Go To Exodus 13
At one time he appears all aglow in a bush. For you are cold with the perfidy of infidelity, and he wants to enkindle you with the heat of faith. At another time he glows like fire in a pillar extending toward heaven, that the darkness of your ignorance may be removed and that you can follow the way of saving knowledge through the wilderness of this world. At yet another time he is changed for you into a pillar of cloud, in order to restrain the burning ebullience of your passions.