Exodus 13:21

21. And the Lord (JEHOVAH) went before them Here now, at Etham, as they enter the wilderness, JEHOVAH himself takes command of the host, and all their marches are supernaturally directed for forty years. Large caravans and armies were often guided in desert marches by a fire elevated in the van. An oft-quoted instance is that of the great army of Alexander, as related by Curtius: “When he wished to move the camp he gave the signal by a trumpet, the sound of which was often not well heard because of the rising tumult. He therefore erected a pole over the imperial tent which could be everywhere seen, from which the signal could appear to all at the same time. A fire was seen there by night and a smoke by day.” (CURTIUS, De Gest. Alex. Mag., 5: 2, 7.) This on a small scale well illustrates what Jehovah now did for Israel. This vast host of at least two millions must often have been spread over several square miles, over the desert plains, up the mountain slopes, and along the wadies, or water courses, in search of pasturage, and they needed some signal that could be seen from far, and this was furnished by the lofty pillar of cloud and of fire. This seems to have been a fire within a cloudy envelope, shining brightly through it in the darkness, and giving it the appearance, in the sunshine, of a lofty column of light smoke or vapour. It rested afterwards upon the tabernacle, the fire then appearing as the SHEKINAH, ( dwelling-place of Jehovah,) and it regulated by its movements all the marches of Israel. Exodus 40:34-38.

As at the burning bramble Jehovah revealed himself to Moses by fire, so now by the same symbol he reveals himself to all Israel; a symbol suited to a people whose mission it was to teach the nations the real nature of God. Fire reveals power without form power the most intense that we know, familiar yet mysterious. Considered as the source of both light and heat, it is an essential of life, genial and gladdening, yet the very emblem of terror and destruction; while at the same time it is the most expressive symbol of perfect purity. Thus the power and the wrath, the holiness and the mercy, of the formless, ever-living Jehovah, are all blended in this emblem. And what more perfect symbol is there of pure spirit, and of that Power whence all other powers spring, than that element or force which is all other material forces in disguise, and into which they all are resolvable?