Based on Naaleh.com shiur by Rabbi Hershel Reichman
The Significance of Four
The number four plays a paramount role at the seder. There are four questions, four cups of wine, four expressions of geulah, four sons, and four letters in Hashem's name, yud keh vav keh. The Shem Mishmuel explains that this corresponds to the four levels of the soul, nefesh, ruach, neshama, and chayah-the biological, emotional, intellectual, and divine aspects of the self.
Our sages say that the Jewish people are characterized by three traits - rachmanim, bayshanim, v'gomlei chasadim, (mercifulness, bashfulness, and generosity). These attributes stem from our forefathers. Avraham signified chesed. Yitzchak, the pillar of yirat Hashem represented bayshanut-humbleness and bashfulness. Yaakov was merciful, a combination of din and chesed. These three middot were passed down to the Jewish people.
The positive side of any spiritual entity has a reverse negative aspect. The evil side of the three middot of the Avot are the three cardinal sins, idol worsip, adultery, and murder. All the sins of the world fall within these three categories. The root of these sins are, jealousy, desire, and honor. Desire is the source of adultery, honor is the root of idol worship as one gives honor to something other than Hashem, and jealousy is the cause of murder. Adultery was counterbalanced by the chesed of Avraham. Yitzchak, with his constant fear of Hashem rectified idol worship. Yaakov, the paragon of mercy, corrected the sin of murder. Moshe, who had the closest relationship with Hashem, symbolizes the divinity in man as represented by chayah. He is the fourth model. The divine image is the key to uniting all the conflicting parts of a person's soul in order to serve Hashem.
The Jewish people went through four subjugations: Bavel, Paras, Yavan, and Edom. Bavel represents idol worship. Paras symbolizes immorality. Yaven signifies murder-a division between Hashem and the world. Edom personifies loshon hara which encompasses all three sins. Egypt was the archetype of all exiles. It was the birthplace of the Jewish nation and it was there that they were tested on all four levels of the soul. Pharaoh issued four decrees. Avodah kasha which affected the nefesh-physical level, killing the male babies before they born which affected the ruach-emotional level, throwing the babies in the river which affected the neshama level. The final decree to collect the straw was meant to wear them out and destroy their divinity. The Shem Mishmuel says that the first two decrees which focused on the physical and emotional level were implemented by the Egyptian people. The last two decrees which were aimed at the Jewish people's higher self- their intellect and divine spirit, were devised by Pharoah. This represents the physical observable world versus the hidden world.
Chazal tell us that the Jewish people merited to leave Egypt in the merit of not altering their garb, language, or name. This was their nefesh, ruach, and neshama expressing itself. Name is nefesh, language is sechel-neshama, and garb is ruach. There was a unity, a wholesomeness, and a tikun at the chaya level. On Pesach we rectify each of the four aspects of our soul. Pesach is the nefesh, marror is the ruach, and matzah is the neshama. Chametz is falsity, a distortion, a lot of hot air. Refraining from consuming chametz rectifies the fourth level, chaya-our divine image.
As explained by the Shem Mishmuel, the number four is important on every level of tikun and the development of the perfect personality. The challenge of Pesach is to achieve sh'leimut. May we merit to experience the tikun klali-the final fixing on all four levels of the soul.