This year is a Jewish leap year, a shana m'uberet. In a Jewish leap year we have two months of Adar. Adar Alef, and Adar Bet. Why did the sages decide the extra month should be an Adar? Why do we need to have leap years in the first place? One reason Rabbi Brovender offered was that we needed to make sure that Pesach would be in the springtime, because it says in the Torah " Today you are leaving in the month of springtime" (Exodus 13:4). So we need to adjust the calendar so that the month of Nisan, and Pesach, would arrive when it is "springy" out. If we didn't add a month every few years, then sometimes Pesach would arrive, and it would still be dark, and cold, and rainy here in Israel. So in days of old, we decided that we needed to declare a year as a leap year, as soon as it was apparent that it wouldn't yet be springy come Nisan. The sages saw, that Adar, here in Israel, is the best time to determine this. Adar is the time to see whether it is going to be dark or light. There is more. Now that the sages decided that there should be two Adars in a leap year, since Purim is in Adar, they also had to decide whether Purim should be in Adar Alef or Adar Bet?! So they had the question: To which month is Purim more similar? Which should it be connected to, near to? Should it be in Adar Alef, and be connected to Shvat, the month that precedes it ,or should it be in Adar Bet, and connected to Nisan? Hmmm...difficult choice.
Well, what are Shvat and Nisan and Purim about? Shvat is a month in the thick of winter. It is very rainy (Thank G-d - really!) and cold, and cloudy, and dark, and things aren't clear at all. Shvat is a month of hiddeness. Nisan, on the other hand, is, as mentioned earlier, in spring. In spring everything is sprouting and budding and coming out of its long winter slumber. The birds start chirping, the flowers blooming, the sky is clearing, and pretty soon it's time for Pesach - time to remember the awesome, revealed miracles that Hashem did for us when He brought us out of Egypt (Mitzrayim). The miracles at Pesach time were obvious to everyone. So, Nisan is a time of revealed redemption. Purim is in Adar, which is right between the two. It's on the border between darkness and light. On Purim we read the Megillat Esther - the Scroll of Esther. The Gemara asks us: Where do we find Esther mentioned in the Torah? The answer is: it says in Devarim 31:18 " V'Anochi haster astir Panai…" which means " And I will surely hide my face…" So we learn that there is a connection between Esther and hiddeness. Also, the name of Hashem isn't written even once in the Megillah! Hashem's guiding hand is hidden in the Purim story. As the story in the Megillah unfolds, it is very hard at first to understand what is happening, or why - but if we look very closely, it's not impossible.
At first, Purim appears to be like Shvat - dark and hidden. But through the efforts of Mordechai and Esther - with their faith and initiative- and the willingness of the Jews to act faithfully (Esther requested " Go, assemble all the Jews to be found in Shushan, and fast for me."), the darkness starts to lift a little. Slowly, slowly, amazing chains of coincidences start to appear.. if we open our eyes to them. For example: Achasverus's feast led to Vashti's execution, and to Esther's coronation. And, as Mordechai says to Esther in the Megillah, "And who knows whether it was just for such a time as this that you attained the regal position!" Now, although not nearly as overtly, Purim begins to look a lot more like Nisan and Pesach - like Hashem's redemption. The difference is that on Purim we really have to CHOOSE to see Hashem's involvement in our lives, and act on it. On Purim it remains in our hands. We can choose to see Hashem's light, through the veils of His world, or not. So, the sages chose to put Purim in Adar Bet, near Pesach, and not in Adar Alef - and they didn't stop there! Not only do the sages want us, and urge us to connect Purim to Pesach (as they said, "smichas ge'ula l'ge'ula" - connect redemption to redemption), they urge us to CHOOSE to seek Hashem when He seems hidden, but they also encourage us to not be apathetic in dark times. They point to this by making the day when Purim could have been (in Adar Alef - in the dark) a day of celebration, suggesting we make a seuda - a festive meal - because that is not the day we have Purim. Because we had a choice and we didn't choose darkness - we didn't accept the decree of our death. We chose light, and life, and Hashem.