Why Drink Four Cups of Wine During Passover?

One of the many facets I find fascinating about Judaism is the stance it takes on alcohol. Views in Christianity vary, but a number of denominations take it to be sinful. In Islam, the Koran (5:90) prohibits the consumption of alcohol. Judaism takes a more positive stance on alcohol. Like with many things in the world, we have the ability to use it in a mundane manner, abuse it, or elevate the mundane into the holy. Judaism takes the third path, and holds the belief that wine can be sanctified in a blessing referred to as Kiddush (קידוש). Kiddush is recited at a number of events: Shabbat, holidays, weddings, brit milah (circumcision ceremony). The Jewish holiday of Passover is different. We don't say the Kiddush over just one cup, but over four cups. You would think that Passover is like other times where one cup is satisfactory. What about Passover is so special that we need to say the Kiddush four times?

1. Passover is referred to as "the time of our freedom" (זמן חרותנו). Wine is historically considered a royal drink. We drink the wine to celebrate freedom (Maimonides, Mishneh Torah, Hilchot Chametz u'Matzah, 7:10), not only that of the ancient Israelites, but of our own freedoms. This could help explain why we drink more wine than on other occasions, but it still doesn't explain why we drink four cups.
2. The Talmud says that (Pesachim 68b) when G-d promised to deliver the Israelites from slavery (Exodus 6:6-8), He used four different phrases to describe the redemption: A) "I shall take you out", B) "I shall rescue you", C) "I shall redeem you", and D) "I shall bring you." Chabad elucidates upon what each of those four phrases means within the context of the four cups of wine. 
3. The words "cup of wine" were mentioned in the Pharaoh's butler's dream (Genesis 40:11-13). The Yerushalmi Talmud (Pesachim 10:3) teaches that the cups of wine allude to Israel's redemption.  
4. The Talmud (Pesachim 117a) states that the four different cups of wine are for four different blessings: one for the wine itself, one for the recitation of the Haggadah, one a blessing over the meal, and one for saying Hallel. 

The two main motifs of the traditional commentary are that of freedom and blessing. Freedom is a blessing. The Israelites were once slaves, but then were freed. As the Passover song Dayenu illustrates, liberation was the beginning of redemption. Redemption came about through free will. We can say "freedom is a blessing," but by reversing that, blessing is a freedom we have. The four cups gives during Passover gives us ample opportunity to appreciate the freedom and redemption that G-d can provide. May this Passover be a time to value our freedoms and count our blessings!