שמות רבה לד ב
א"ר שמעון בן יוחאי: ג' כתרים הם, כתר מלכות וכתר כהונה וכתר תורה. כתר מלכות זה השלחן דכתיב בו "זר זהב סביב". כתר כהונה זה המזבח דכתיב בו "זר זהב סביב". וכתר תורה זה הארון דכתיב בו "זר זהב".
and
במדבר רבה ד סוף סימנים יג יד
רבי שמעון אומר שלשה כתרים הם כתר תורה וכתר כהונה וכתר מלכות וכתר שם טוב עולה על גביהן. מעשה הארון כנגד בעלי תורה ... מעשה השולחן כנגד מלכות בית דוד ... מזבח הזהב כנגד כתר כהונה ... מעשה מנורה כנגד בעלי שם טוב , שנאמר: טוב שם משמן טוב, ולכך היו כל כליה עמה בבגד תכלת שכתר שם טוב על גביהם
אבות פרק ד משנה יג
רבי שמעון אומר: שלשה כתרים הם: כתר תורה וכתר כהונה וכתר מלכות. וכתר שם טוב עולה על גביהן.
Yoma 72b
אמר רבי יוחנן שלשה זירים הן, של מזבח, ושל ארון ושל שולחן
Rashi says in Yoma there,
שלשה זירין נעשו בכלי הקודש. של מזבח סימן לכתר כהונה ושל ארון סימן לכתר תורה ושל שולחן סימן לכתר מלכות, שהשולחן הוא סימן לעושר מלכים
Many mefarshim ask, where is the fourth crown? If, as the Mishna in Avos says, the greatest crown is that of Shem Tov, why is that crown not found in the Mishkan? And now that the Medrash in Bamidbar says that the Menora represents that crown, why did the Menorah not have any crown? If the symbolic crown appeared on the Shulchan, the Mizbei'ach, and the Aron, why did the Menorah have no crown at all?
There are many teirutzim to this question, beginning with the Maharal in Derech Chaim in Avos. But the ellipsis is obvious and clearly intentional, and so I think it deserves a simple and satisfying answer. (H. L. Mencken once wrote that "For every complex problem there is an answer that is clear, simple, and wrong." Unlike most such answers, I think this one is good.)
A כתר-זיר-crown is a symbol of greatness. By placing a crown on top of a person or a thing, you express its glory. But it is only a symbol. What a crown expresses is splendor, a shine. In fact, the idea of a crown is most fundamentally expressed in Iyov 29:2-3,
מי יתנני כירחי קדם כימי אלוה ישמרני. בהלו נרו עלי ראשי לאורו אלך חשך
There, we see the crown as a halo, a ring of light. That is a true crown, symbolically expressed by placing a gold crown on one's head. In fact, the words זהב and זיב , gold and shine, are basically the same. We use gold to represent and produce a zohar/ziv. In the same way, the words זר and זוהר are essentially the same- a crown, and a shine. The purpose of the זר is to represent and embody a זוהר.
But the Menorah did not need a symbolic crown. The purpose of the Menorah was to cast light, and that light is an inherent crown. The Menorah, which represented the Keser Shem Tov, did not need a golden crown. It did not need זהב, because it had זיב , and it did not need a זר because it had a זוהר , and it did not need a קרן של זהב because it had קרני אור. It did not need a crown, because it had a Corona. When you have a halo, it doesn't make any sense to wear a crown.
After Mattan Torah, the members of Klal Yisrael had עדיים, crowns of glory, which they had to give back after the Eigel. But Moshe, as far as I know, did not have any עדי. He had Karnei Ohr, and he didn't need any עדיים.
One last thing. An answer as simple as this will often evoke the reaction that it is so obvious that everyone knows it without being told. If,you feel that way, why don't you ask someone the question. "If" they don't give this answer immediately, tell them to think about it for a while and come back to you with an answer. Then you'll see how obvious it is. The only criticism I accept on this answer is that it doesn't offer anything meaningful from a hashkafa or chochma standpoint. It's just a simple fact.
After Mattan Torah, the members of Klal Yisrael had עדיים, crowns of glory, which they had to give back after the Eigel. But Moshe, as far as I know, did not have any עדי. He had Karnei Ohr, and he didn't need any עדיים.
One last thing. An answer as simple as this will often evoke the reaction that it is so obvious that everyone knows it without being told. If,you feel that way, why don't you ask someone the question. "If" they don't give this answer immediately, tell them to think about it for a while and come back to you with an answer. Then you'll see how obvious it is. The only criticism I accept on this answer is that it doesn't offer anything meaningful from a hashkafa or chochma standpoint. It's just a simple fact.
But one question does remain. Assuming that the light of the menora is the crown that corresponds to the Keser Shem Tov, why is the menorah and its light the best metaphor for that Keser? The shulchan, the mizbei'ach, the Aron, are obviously appropriate. But what is it about the Menorah that corresponds davka with Keser Shem Tov?
My initial response is that without the light of the Menorah/Shem Tov, the other kesarim remain in the dark and lose their significance. What good is a Talmid Chacham without Da'as? Or a Kohen that is unpleasant and unsympathetic? Or a King that walls himself off in his Versailles? Only when they have a shem tov can their other qualities become an additional crown.
I'm open to suggestions.