A person is obligated to become intoxicated on Purim

חייב איניש לבסומי בפוריא

The Sages state: "A person is obligated to become intoxicated on Purim to the extent that he does not know the difference between 'Cursed is Haman' and 'Blessed is Mordechai.'" (Megillah 7:2)
Talmud relates: Rabbah and Rav Zeira celebrated the Purim. They became intoxicated. Rabbah stood up and slew Rav Zeira. The day after, he prayed for mercy and brought him back to life.

The following year,  Rabbah  again invited  Rav Zeira  to celebrate the feast together. Rav Zeira answered him: "A miracle does not happen every moment." The story begs explanation. How is it possible that a leading Talmud Sage performed an act that - if not for a miracle - would have resulted in a colleague's death?

1. The Maharsha explains that Rabbah did not actually slay Rav Zeira. Instead, he compelled him to drink extensively until he became sick and was on the brink of death.
2. This interpretation, however, does not fit the simple meaning which speaks of Rav Zeira being killed and then "brought back to life."
3. Compelling a person to drink to the point that his life is in danger, is not appropriate for a Torah sage.
4. Another element: Rabbah's invitation to Rav Zeira to repeat the feast the following year.
5. The Talmud explains that he was prepared to share a Purim feast with Rav Zeira again despite the possibility of a recurrence of the events of the previous year.
6. What is Rav Zeira's answer? He did not refuse Rabbah's invitation categorically. Instead, he told him: "A miracle does not happen every moment," implying that he would like to accept Rabbah's offer, but could not because he was not sure that the miracle would repeat itself.

Some say the story reflects spiritual concepts. But it would be wrong to say that it is a mere allegory, for: the story is quoted as an example of the fulfillment of the directive: "A person is obligated to become intoxicated on Purim...." Just as the law must be fulfilled in actual deed, so too, the example must have actually occurred.

Rabbeinu Efraim uses the example of Rabbah's conduct to argue that the Talmud did not accept the law that "A person is obligated to become intoxicated on Purim...." From either perspective, it is clear that the story of Rabbah and Rav Zeira is not merely a spiritual allegory, but is an event that actually took place.

Thus an explanation must be found which: interprets the story according to its simple meaning - that the two Sages actually became intoxicated and Rabbah caused Rav Zeira's death - and yet; projects an image of the Sages that is befitting their spiritual stature, one which explains how Rabbah's actions can in no way be associated with murder and why Rav Zeira would have desired to repeat the feast the following year.

"When Wine Enters, The Secrets Come Out" A resolution can be reached through comparison to another tragedy associated with excessive drinking: the death of Aharon's sons Nadav and Avihu.
Our Sages state they died because they entered the Sanctuary while intoxicated. In this context, a question is raised: Aharon's sons were on a high spiritual level. Moshe himself said that their refinement was above his own and that of Aharon. How then was it possible for them to conduct themselves in such an undesirable manner?
The Or HaChayim explains the death of Nadav and Avihu was because they came close to a sublime light with holy love and died because of it. This is the mystic secret of "[G-d's] kiss" through which the righteous die. Their death was equivalent to the death of the righteous. On this basis, we can understand our Sages' statement that they entered the Sanctuary intoxicated. Wine is sod of the Torah as alluded to in our Sages' expression: "When wine enters, the secrets come out." Intoxicated with wine implies that the appreciation of these mystic secrets overwhelmed their powers of conception, and lead them to an inextinguishable yearning for G-d, resulting in the expiration of their souls. This allegoric interpretation is not, however, divorced from actual fact. In addition to partaking of the Torah's mystic secrets, Aharon's sons also drank actual wine. Since they were holy, the release of inhibitions which alcohol causes spurred their spiritual potentials.
We find a parallel to this in a testimony of the Sheloh who speaks of exceedingly holy people: Drink[ing] much more than ordinary at large feasts... with an intent for the sake of heaven... They were in very good spirits and therefore, recited many Torah teachings.... For due to a spirit of happiness, a wise man will reveal the Torah's mystic secrets.... as implied by the expression, "When wine enters, the secrets come out." The Dangers of Over-Exposure Thus, we can understand the intoxication that occurred at Rabbah and Rav Zeira's Purim feast. Rabbah and Rav Zeira partook freely of the "wine of Torah," they delved deeply into the Torah's mystic secrets. Rav Zeira died, i.e., his soul expired in yearning for G-dliness like the souls of Aharon's sons.

Why does the Talmud say that Rabbah "slew Rav Zeira"? The precise word the Talmud uses for slay is vishachat. When the Talmud describes a killing, it uses the word ketal. Shachat is the term used to refer to ritual slaughter. In the latter context, our Sages said: "The sole meaning of vishachat ("and he slaughtered") is umashach "and he drew after." The name Rabbah means "the great one", i.e., he had a broad intellectual capacity. The name Zeira means "the small one", i.e., he had a more limited capacity. During their feast, while Rabbah and Rav Zeira were indulging in deep mystic secrets - and drinking wine, in a manner parallel to that described by the Sheloh, Rabbah "stood up," i.e., he rose to a higher level of mystic understanding. Vishachat liRav Zeira, "he slew Rav Zeira," i.e., he drew Rav Zeira after him, sharing his knowledge with him. But because Rav Zeira did not have as great an intellectual capacity, he was unable to control himself, and his soul expired. Rabbah's responsibility for Rav Zeira's death is thus merely an error of judgment; he thought that Rav Zeira could, as Rabbah himself did, contain his soul despite becoming aware of these mystic truths. Moreover, since Rabbah had the power to bring Rav Zeira back to life, the experience of kalos hanefesh, that Rav Zeira's soul expired in love for G-d, was not a negative one.

Ultimately, Rav Zeira was also able to "depart in peace," and return to a measured and controlled path of Divine service within this world. Forced To Decline An Invitation We can understand Rav Zeira's response to Rabbah's invitation the following year. Both Sages wanted to repeat the experience. Rabbah hoped that in the year that had passed, Rav Zeira had progressed in his Divine service to the point that he would be able to receive the mystic secrets from Rabbah without his soul expiring. Rav Zeira also desired to taste these spiritual heights.
Yet, he had to decline the invitation. For he realized that the ultimate intent is to serve G-d within the context of our material existence. He was not sure that he would be able to contain his soul in the face of the powerful revelations and feared that it would expire again. And since "A miracle does not happen every moment," he was not willing to take the risk that he would not be able to continue his life on the material plane. Knowing - And Not Knowing As mentioned above, the story of Rabbah and Rav Zeira is quoted as a support for the law that "A person is obligated to become intoxicated on Purim to the extent that he does not know the difference between 'Cursed is Haman' and 'Blessed is Mordechai .'" The fact that this law is accepted by the Shulchan Aruch indicates that we do not fear negative consequences, that Purim is a time when every person can rise to unbounded levels of love for G-d, and yet, return to controlled and measured Divine service on the material plane. For the heightened experience of this one day will impart energy and vitality to one's Divine service for the entire year.