At the beginning of the Torah portion Va'eira, four expressions are used with regard to the redemption from Egypt: "I will release you... I will save you... I will liberate you... I will take you...."
Our Sages note that the four cups of wine which we drink during the Passover Seder correspond to these four expressions.
Accordingly, the following question arises:
Bearing in mind that we eat Matzah on Passover "because our ancestors were liberated from Egypt," why do we not eat four Matzot, just as we drink four cups of wine? Why do we take only three Matzot to the Seder?
Evidently, there must be two aspects to the exodus from Egypt, one that is composed of three details and one that is made up of four.
What are these two aspects?
At the time the Jewish people departed from Egypt they were not yet spiritually worthy of redemption. In fact, had they remained one more moment in Egypt, they would have become forever mired in impurity.
Notwithstanding their state of depravity, G-d in His infinite kindness revealed Himself to them and redeemed them.
This is why the completion of the exodus came about only when the Jews received the Torah, for complete liberation from Egypt required that the newborn nation rid itself of Egyptian impurity.
This was accomplished as the Jews prepared themselves in the days between the exodus and the receiving of the Torah; they achieved such heights that by the time the Torah was given they could justifiably be called a "holy nation."
The difference between the symbolism of "Matzah" and "wine" will be understood accordingly:
Matzah emphasizes the aspect of the exodus that came about as a result of G-d's redemption from the impurity of Egypt.
It is for this reason that Matzah is called "impoverished bread" bread that lacks taste - for it is a remembrance of spiritual impoverishment.
"Taste" refers to something a person can appreciate in some way.
Since the liberation from Egypt originated from Above rather than from the spiritual preparation of the Jewish people, it is understandable that it lacked "taste" - the Jews were compelled to leave.
Wine, however, has taste and is enjoyable.
It is a "remembrance of the liberation and freedom" ultimately achieved by the Jews, i.e., it was through their own service that they were redeemed from the evil of Egypt.
The reason for three Matzot vis-a-vis four cups of wine now becomes clear:
There is a difference between the first three expressions of liberation and the fourth, in that the first three - "I will release you... I will save you... I will liberate you" - are aspects of redemption that took place immediately upon the departure from Egypt; they came from Above.
The fourth expression - "I will take you unto Me as a Nation" - however, depended on the Jewish people; they had to become worthy of being called G-d's nation. This was accomplished when they received the Torah.
Thus, Matzah is equated with the number three, corresponding to the first three expressions of liberation, inasmuch as Matzah commemorates the redemption as it came from Above.
The cups of wine, however, allude to the liberation accomplished by and within the Jewish people.
The cups are therefore equated with the number four, for they denote the fourth expression of redemption - "I will take you unto Me as a Nation."
Adapted from the works of the Lubavitcher Rebbe, Rabbi Menachem M. Schneerson, of righteous memory. (Likkutei Sichos Vol. XXVI, pp. 43-46.)