To understand the musaf kedushah, we have to compare it to the shacharit kedushah. Every kedushah is an attempt to imitate the angels who form the divine retinue. We proclaim G-d’s holiness the way the angels did in Isaiah’s heavenly vision (kadosh, kadosh, kadosh… “holy, holy, holy….” We then make reference to Ezekiel’s heavenly vision, wherein the angels declare “Praised be the glory of G-d from His place.” (baruch kvod malchuto…)This is followed by the proto-Zionistic hope that G-d will come forth from the above mentioned place and reign in Jerusalem. And then we express the wish that, as mentioned in the psalms of “David mashiach” (note the messianic reference), G-d will reign forever and ever over the people of Zion. (yimloch ad-nai l’olam…).
In the musaf kedushah, another crucial element is added. Unlike the shacharit kedushah, where we simply express our hope that G-d will return to Zion, in the musaf kedushah we “up the ante.” We make a point of mentioning that every night and day we proclaim the oneness of G-d with love, by saying the shema. And we go a step further and assert that eventually G-d will make a proclamation before the whole world that “I am the Lord your G-d”—the words with which the biblical shema text concludes.
In other words, the human posture in the shacharit kedushah is passive, or merely imitative: we mimic the angels (hence the tradition of rising up on our toes three times while saying kadosh, in imitation of the angels) and express our hopes for redemption. The human posture in the musaf kedushah is much more active. Beside our imitation of the angels, we make our own, unique, profoundly human, and profoundly Jewish declaration—that G-d is One—and interweave it with G-d’s own universal divine declaration yet to come.
May we hear it quickly, in our days.
Rabbi Robert L. Wolkoff