According to rabbinic tradition, on the seventh day of Passover the Children of Israel crossed on a dry path through the Sea of Reeds. They were pursued by the hosts of Pharaoh, who, upon entering the sea, drowned in the waters when they returned to their normal course. In Megilla 31a, it is specified that this story, which appears in Exodus 14-15, be assigned as the Torah reading for the seventh day of Pesach. This attests to the antiquity of the tradition of relating Exodus 14-15 to the seventh day of the feast.
The sages of the Talmud compare in a famous midrash (Mekhilta deRabbi Ishmael, Beshalach, Masekhta de-Vaiehi 6) the plagues suffered by the Egyptians in their own country with their countrymen who suffered at the sea. This midrash is part of the text of the Passover Haggadah. In the same way that the song that Moses and the people sang when they passed through the sea is read in the sedarim, so, too, it is read again on the morning of the seventh day, the last feast day of Pesach in the land of Israel. One can infer that the process of liberation began on the first day of the festival and culminated on the last. Seen in this way the seven days describe the strains of a liberation process.
The Passover message, although it is distinctive of Israel, extends to all humanity. For centuries humanity has been struggling in a process whose ultimate goal should be the construction of a reality of peace, spirituality, concord and freedom among all peoples and nations. The Haftara, the readings from the books of the prophets that accompany the Torah readings, is on the eighth day of Passover (in the Diaspora) Isaiah 10:32-12:6. In that passage Isaiah describes his vision of messianic times. In those days, the ultimate realization of human freedom and dignity will be realized, and the message of Pesach will become a reality over the face of the earth.