“platform.” Although the Hebrew word raqiva (#07549 רָקִיעַ) is usually rendered “firmament,” “dome,” or “expanse,” there is good lexical and contextual reason to translate it as “platform” here; a platform with Yahweh’s throne set on it (cp. NET, Word Biblical Commentary; The New International Commentary on the Old Testament; Hermeneia Critical and Historical Commentary; The Anchor Bible: Ezekiel; Tyndale Old Testament Commentaries: Ezekiel. And compare also NJB, NRS, and NLT).
The Theological Wordbook of the Old Testament says that the basic concept of the Hebrew root of raqiva is “stamping, as with the foot, and what results.” Thus, raqiva referred to broad plates, beaten out. We certainly see this when the Septuagint, the Greek translation of the Old Testament, translated raqiva as stereōma, a solid supporting structure. The Brown-Driver-Briggs Hebrew-English Lexicon gives one of the two definitions of raqiva as “the vault of heaven, or ‘firmament,’ regarded by the Hebrews as solid, and supporting ‘waters’ above it.” The Holladay Hebrew-English Lexicon says that raqiva refers to a beaten metal “plate, firmament (i.e. vault of heaven, understood as a solid dome).”
The Latin Vulgate translated raqiva as firmamentum, referring to something which strengthens or supports, thus a firm structure, and that came into the English as “firmament,” which lexically means the same as the Latin, something firm that strengthens or supports. However, because of its use in Genesis and a lack of understanding of the Hebrew cosmology, the “firmament” lost its attachment to something firm, and was thought to refer to an expanse, the expanse of heaven. Many people today think it refers to the expanse of heaven, but we must keep in mind that the ancients thought of the “expanse of heaven” as a kind of hard dome over them, an expanse that had some solidness to it. The concept of “infinite space” was not a cosmological concept in the ancient near east.
The important point for understanding Ezekiel is that the raqiva, the “firmament,” was not thought to be an empty expanse of air, like we moderns might imagine. Even as an “expanse,” it was a hard surface that extended out into the distance. Ezekiel used raqiva as a hard surface, but as the hard platform that was above the cherubim and upon which God’s throne was placed.
It has been traditionally thought by many (and with good reason) that above the cherubim was an “expanse” like described in Genesis, the expanse of heaven, and God’s throne was above it. But while that seemed logical, it makes Ezekiel’s vision impossible to understand. If God is in heaven on His throne, what is the point of the cherubim with four wings and the wheels beside them coming to Ezekiel? This vision makes sense to us once we realize that the cherubim and wheels are part of God’s chariot-throne and God’s throne is on a platform above the cherubim.
It seems that the cherubim were such a vital part of God’s chariot-throne that when the ark of the covenant with the mercy seat and cherubim are being described as a centerpiece of Solomon’s Temple that the cherubim are even called, “the chariot” (cp. 1 Chron. 28:18).
“glittering.” This is the same word as it translated “eye” in Ezekiel 1:18 (see commentary on Ezek. 1:18, “eyes”).
“like crystal.” The Hebrew word (#07140 קֶרַח), which often refers to ice and could refer to that here, also can refer to crystal, hence the different English translations. Both ice and crystal can glitter and shine awesomely in the sunlight. Also, both crystal and ice are clear enough that Yahweh could see the cherubim and wheels, and anything else beneath Him, and the cherubim could watch Him.