The juxtaposition of Purim and Pesach is a halachic requirement. In a leap year, Purim is celebrated in the second Adar, the one closest to Nissan, so that the two redemptions, from Pharaoh and from Haman, will be celebrated in consecutive months (Megila 6b).
This halacha reflects a fundamental article of faith articulated by the Ramban (Shmos 13:16). From the great and obvious miracles, a person should deduce and recognize the hidden miracles, which are the basis of the entire Torah. Pesach, the anniversary of overt miracles, must be connected to Purim, the holiday of hidden miracles.
The Ramban adds that the nissim nistarim are revealed when Am Yisroel is punished for abandoning the Torah and rewarded for observing it. Even the nations of the world recognize this (Devarim 29:13, 24 and 28:10). Moreover, Hashem's only desire is that man recognize this truth and publicize it by communal prayer in a loud voice, as the people of Ninveh did (Yona 3:8).
"Just as when Av begins we decrease joy, so too when Adar begins we increase joy" (Taanis 29a). Rashi explains that the increased level of joy continues through the days of Purim and includes Pesach, further underscoring the close connection between the two holidays.
The contrast between Av and Adar requires further analysis. The phrase "just as" (k'shem) implies a logical relationship. We must, therefore, delve into the root causes of Tisha B'Av on one hand, and Purim and Pesach on the other.
The earliest tragedy of Tisha B'Av was the sin of the spies (Ta'anis 29a). What was their mistake? The meraglim saw the punishment of Miriam, but failed to learn a lesson from it. For this reason, the story of the meraglim is found right after the story of Miriam (Rashi, Bamidbar 13:1). What lesson should the meraglim have learned from Miriam; their sin was not lashon hara, but motze shem ra on an inanimate object, Eretz Yisroel (13:32, see Onkelos)?
Miriam had discovered that Moshe abstained from relations with his wife, and related this fact to Aharon (Rashi 12:1). They said, "Hashem spoke to us too, yet, we have not abstained from marital relations (Rashi 12:2)." For this, Miriam was punished, even though she did not intend to speak badly of Moshe (Rashi 12:1). Hashem tells Miriam and Aharon that He had told Moshe to abstain (Rashi 12:8). He becomes angry and afflicts Miriam with tzara'as.
Miriam's basic mistake was the misinterpretation of the facts. She thought that Moshe had decided on his own to abstain, and she questioned his decision. In reality, however, Moshe was commanded to do so by Hashem. Miriam's lashon hara was caused by her incorrect understanding of Moshe's situation.
The meraglim made a similar mistake. They described Eretz Yisroel as a land that devours its inhabitants (13:32). Wherever they went, they saw burials, so they assumed that it is extremely dangerous to live there (Rashi). In reality, Hashem arranged for numerous deaths and burials for the forty days the meraglim were in Eretz Yisroel in order to preoccupy the natives of the land with their mourning so that they should not detect the spies. At all other times, Eretz Yisroel was not dangerous at all.
The lesson that the meraglim should have learned from Miriam was the need to be certain about the facts before criticizing a person or a land. Miriam could have asked Moshe, or perhaps even Hashem, why he abstained. Similarly, the meraglim could have asked Moshe, or perhaps even Hashem, why so many people died in Eretz Yisroel. Instead, based on their misinterpretation, they criticized Moshe and Eretz Yisroel, respectively.
Likewise, the tragedy which sealed the fate of the first Beis Hamikdosh was based on a misinterpretation of the facts. King Yoshiyahu did not allow Pharoh Neco to pass through Eretz Yisroel on a military campaign. He thought that idolatry was eliminated, and that the Jews were worthy of the bracha, "and a sword will not cross your land, even to pass through," (Rashi Vayikra 26:6). In reality, many Jews hid their idols by splitting them between the doors and the doorposts, thus evading Yoshiyahu’s inspectors. Yirmiyahu warned the king to let Pharoh Neco pass through. Yoshiyahu ignored the prophet and was killed by the Egyptians, ending the last chance to avoid the churban and Galus Bavel (Midrash Eichah 1:53).
Contrast the causes of Tisha B'av with the story of Purim. The exiled Jews were threatened with extinction by Haman. Enraged by Mordechai's refusal to bow to him, Haman persuaded Achashverosh to exterminate all the Jews (Esther 3:5-13). The basic facts indicated that Mordechai was to blame for the terrible death threat. In reality, however, the Jews were doomed because they enjoyed the banquet of Achashverosh (Megilla 12a), which had taken place nine years earlier (1:3). When told of this by Mordechai, the Jews accepted this improbable cause, and repented by fasting and reaccepting the Torah (9:27). Hashem, through a nes nistar, reversed their fate, allowing the Jews to prevail over their enemies, leading to the joy of Adar and Purim. (See Michtav MeEliyahu p.76.)
Similarly, when Am Yisroel left Egypt, the logical strategy was to flee. Yet when Moshe told them to move closer to their pursuers, they said: we rely only on the words of Moshe (Rashi Shmos 14:4). This led to the nes nigleh of Kriyas Yam Suf. Thus, the increase in joy during Purim and Pesach reflects the correction of our mistake of Tisha B'Av, which led to the decrease in joy.
This timeless lesson has direct relevance today. The press analyzes the military and political crisis in Eretz Yisroel ad nauseum. The relative strength of armies and terrorists, the attitudes of presidents, prime ministers, and chairmen are scrutinized and constantly reevaluated. As believing Jews, we must recall the words of the Ramban. Am Yisroel is punished for its failure to observe the Torah properly, and the appropriate response to crisis is loud communal prayer, accompanied, as in Ninveh, by fasting and repentance.
Of course, political and military leaders must pursue solutions, however elusive they seem. But Am Yisroel must daven, fast and do teshuva. We dare not repeat the mistakes of Tisha B'Av, by accepting situations in Eretz Yisroel at face value, which led to incorrect despair and unwarranted confidence, respectively. We must think of Purim, when we fasted and repented on Mordechai's instruction that our sins, not kings, or adherence to principle, caused the grave threat. And of Pesach, when we followed Moshe and not conventional military strategy.
Unfortunately, today we have no prophets to tell us what to do and for what to repent. However, we should be guided by our Torah leaders in our response to the crises in Eretz Yisroel, and should do teshuva to the best of our ability.
As we moved from Adar to Nissan, thousands of Jews worldwide fasted and gathered to pray aloud. Hopefully, Hashem will respond and save us naturally, as on Purim, or, even better, supernaturally, as on Pesach. May Nissan 5762 be the one about which it is written (Rosh Hashana 11a), in Nissan we will be redeemed, Amen.