The Ark of the Covenant
"They shall make an ark of acacia wood, two and a half cubits its length, a cubit and a half its width, and a cubit and a half its height. You shall overlay it with pure gold; from inside and from outside you shall overlay it, and you shall make upon it a golden crown all around" (Shemot 25:10-11).
The Ark of the Covenant was the first item in the Mishkn that God commanded Isael to make. That is because it was the most important and holiest part of the Mishkan.
It was only piece of furniture that was in the Holy of the Holies, the Mishkan's inner sanctum, and it was the place from which: "I will arrange My meetings with you there, and I will speak with you from atop the ark" (ibid 22).
Amazingly enough, this holiest of items had on it two images, two golden cherubs "wings spread upwards, shielding the ark cover with their wings, with their faces toward one another" (ibid 20), in total violation of the Ten Commandments: "You shall not make for yourself a graven image or any likeness which is in the heavens above, which is on the earth below, or which is in the water beneath the earth. You shall neither prostrate yourself before them nor worship them" (ibid 20:4-5).
How was it possible that Israel's holiest object contained two images?
Interestingly enough, the Ark and the cherubs on it, were never meant to be seen. As we noted earlier, the Ark was placed in the Holy of Holies. No one was ever allowed in there, save the Kohen Gadol, the High Priest, on Yom Kippur. Yet even then, he never actually saw the Ark because before he went it "he shall place the incense upon the fire, before the Lord, so that the cloud of the incense shall envelope the ark cover that is over the [tablets of] Testimony, so that he shall not die" (VaYikra 16:13). The smoke from the incense was to envelop the Ark before, the Kohen Gadol went in, so he never actually aw it.
Even when the people traveled it was never seen, because: "Aaron and his sons shall come and take down the dividing screen; with it, they shall cover the Ark of the Testimony" (Bemidbar 4:5). Therefore, the Ark was always covered with the parochet when it was not in the Holy of Holies.
Furthermore, while the Ark may have been used to lead in Israel in battle in Israel's infancy, it is clear from the Sefer Shmuel, when Israel decided to bring the Ark to battle, and the Philistines shouted in woe: "was nothing like this yesterday and before yesterday" (1 Shmuel 4:7) that this practice soon stopped.
Even more interesting is the fact that despite the Ark being the most important item, it did not feature at all during the Second Temple yet the Temple functioned well without it. Indeed, it is now The Lost Ark, and it is unlikely that it will ever be re-discovered.
Therefore, it is possible to understand the Ark and its cherubs as a concession to ancient Israel's evolution from idolatry to monotheism. The young nation, brought up on Egypt's plethora of gods, found the concept of an imageless God an impossible concept to comprehend. In the circumstances, they were given an image, but they could never see it. Overtime, the Ark itself became lost; as Israel developed an no longer even needed a hidden image.
Last year's Sedra Short on Parshat Teruma, entitled: "The Keruvim" appears at http://parshablog.blogspot.com/2008/02/parshat-teruma-keruvim-keruvim-cherubs.html
Another Sedra Short on Parshat Teruma, entitled: "Living With God" appears at http://parshablog.blogspot.com/2007/02/parshat-teruma-living-with-god-in.html
A further Sedra Short on Parshat Teruma, entitled: "A Home for God" appears at http://parshablog.blogspot.com/2006/02/parshat-teruma-home-for-god-god-told.html