"It is not in the Heavens"
Summarized by Hillel Meizels
"R. Acha in the name of R. Yosi bar Chanina said: When Moshe went up (to receive the Torah) he heard God's voice dealing with the parasha of para aduma (the red heifer) and stating halakha in the name of the one who said it: 'R. Eliezer says ...a cow has to be in its second year (to be fit for use as a para aduma).' ...Moshe said to God: 'May it be Your will that he be one of my descendants.' God said to him: 'Upon your life, he IS of your descendants, as it is written: "And the name of THE ONE is Eliezer" - and the name of that special one is Eliezer.'" (Midrash Tanchuma, Chukat, 24)
Our human concept of "oneness," completeness, wholeness, is not the same as God's. A human can have conflicting emotions, can change his opinions from one day to the next and can act hypocritically. God, however, is completely unified. His different attributes are in total harmony and all contribute to His oneness.
By referring to R. Eliezer, a human, as THE ONE, God was saying that R. Eliezer was the human being closest to the state of Godly oneness, and therefore, God took pleasure in quoting the halakhot in his name. What makes this strange is that this is the same R. Eliezer who was placed under a cherem (ban) by the rest of the sages in the famous case of the "tanur shel Achnai" (Bava Metzi'a 59b). This was an oven made of separate tiles, connected with sand-cement. R. Eliezer held that if an impure substance was placed in it, the whole oven remained pure, while the sages held it became impure. R. Eliezer brought many miraculous signs to show that he was correct, but the sages stood firm in their decision. R. Eliezer then called on heaven to prove that he was right. A bat kol (heavenly voice) called out: "What are you doing to R. Eliezer, for the halakha is like him in every place?" R. Yehoshua stood up and said: "It is written: 'It [the Torah] is not in the heavens (Devarim 30).' What does this mean? That the Torah was already given on Har Sinai and [now] we do not pay attention to a bat kol [to decide halakhic issues]." R. Natan later asked Eliyahu what God's reaction was at the time. Eliyahu replied: "God smiled and said: 'My sons have defeated me, My sons have defeated me.'"
The sages proceeded to reverse all R. Eliezer's decisions in which he proclaimed something pure, and they burnt those objects (as they were now impure). They then got together and put R. Eliezer under a ban. The gemara continues to describe how upset R. Eliezer was and the upheavals that took place in the world due to his anguish. When Rabban Gamliel's ship was then threatened by a storm, he called out to God that he had banned R. Eliezer in order to maintain God's honor, i.e. so that there should not be many arguments within Yisrael.
This incident only serves to highlight R. Eliezer's standing in the eyes of God and it seems very strange that a man so great should be put in cherem by the rest of the sages. To understand this better, we first have to understand one of the laws of tum'a (impurity).
Any vessel which comes into contact with something tameh (impure) is rendered tameh as well. However, if the vessel is slightly broken or cracked or made from different pieces, it can not be rendered impure. It is only fit to become tameh if it is complete, whole.
Now we can apply this to the tanur shel Achnai which was made of tiles connected by sand-cement. When R. Eliezer came to determine the status of the oven, he looked at it from heaven's viewpoint of completeness and wholeness. From that lofty perspective the oven was not at all whole. Therefore, it could not become tameh and R. Eliezer pronounced it tahor (pure). However, from that perspective, nothing in this physical world is ever really complete. The sages realized this and therefore judged the oven from a realistic, worldly perspective. From this point of view, the oven was whole and therefore tameh. The sages understood that we can't live our lives in this world, which is bound by physical limits, according to the high standards of heaven. True, we have to draw from the spiritual, the Godly, and strive towards it, but the halakhic norms of our lives must be established by the practical, physical limitation of the world we live in. We cannot establish halakhic reality in this world based on Heaven's high standards.
Now we can understand why the sages denounced R. Eliezer and all his halakhot, because these were not judged by the criteria of the human beings for whom they were aimed, but rather by heaven's standards. But halakha is meant for human beings and not angels. We can also understand how R. Eliezer was able to call forth all those miraculous signs: by heaven's standards, he was correct and so he received God's support, to the point of having a bat kol support his position.
One question remains. Surely God was the one who established that halakha must be judged in accordance with the requirements of this physical world; He was the one who said: 'It is not in the heavens.' So why did the bat kol defend R. Eliezer?
The answer is simple enough. Although by heaven's standards R. Eliezer was right, God obviously knows that we are living in this physical, limited world and are bound by it. By sending out a bat kol he was testing the sages to see if they would stand by their principles, even to the point of God himself seemingly going against them. If they could withstand this, they could withstand any type of adversity, and would always continue to determine halakha appropriately.
(Originally delivered at Seuda Shelishit, Shabbat Parashat Chukat 5755.)