Ewald's view is that the smoke of the altar which went up in a thick column, visible at a great distance by day, ruddy with flame by night, was the origin of the conception. There are various objections to this theory, which the author of it himself finds difficult to reconcile with many of the statements. At the same time the pillar of cloud does not need to be thought of as in any respect a more Divine symbol than others which were associated with the tabernacle. Certainly the ark of the covenant which Bezaleel made according to the instructions of Moses was, far beyond anything else, the sacred centre around which the whole of the worship gathered, the mysterious emblem of Jehovah's character, the guarantee of His presence with Israel. It was from the space above the mercy-seat, as we have seen, that the Voice proceeded, not from the pillar of cloud. The sanctity of the ark was so great that it was never exposed to the view of the people, nor even of the Levites who were set apart to carry it. The cloud, on the other hand, was seen by all, and had its principal function in showing where the ark was in the camp or on the march.
Now assuming, in harmony with the reference in Isaiah, that the cloud was one of smoke, some may be disposed to think that, like the ark of the covenant, the holiest symbol of all, this was produced by human intervention, yet in a way not incompatible with its sacredness, its mystery, and value as a sign of Jehovah's presence. Where Moses was as leader, lawgiver, prophet, mediator, there God was for this people: what Moses did in the spirit of Divine zeal and wisdom was done for Israel by God. Through his inspiration the ritual and its elaborate symbolism had their origin. And is it not possible that after the manner of the emblem of Jehovah which appeared in the desert of Horeb the fire and cloud were now realised? While some may adopt this explanation, others again will steadily believe that the appearance and movements of the cloud were quite apart from human device or agency.
Scarcely any difficulty greater than that connected with the pillar of cloud presents itself to thoughtful modern readers of the Pentateuch. The traditional view, apparently involved in the narrative, is that in this cloud and in this alone Jehovah revealed Himself in the interval between His appearance to Jacob and, long afterwards, to Joshua in angelic form. Many will maintain that unless the cloud was of supernatural origin the whole relation of the Israelites to their Divine King must fall into shadow. Was not this one of the miracles which made Hebrew history different in kind from that of every other nation? Is it not one of the revelations of the Unseen God on which we must build if we are to have sure faith in the Old Testament economy, and indeed in Christianity itself, as of superhuman revelation? If we are not to interpret literally what is said in Exodus--"The Lord went before them by day in a pillar of cloud, to lead them the way; and by night in a pillar of fire, to give them light"--shall we not practically abandon the whole Divine element in the history of Israel's deliverance and education? Thus the difficulty stands.