Time and place are two fundamental coordinates of life, and, in particular, of Jewish life and teaching. As regards "place," the Torah focuses on the Holy Land, the site of the Temple and the sacred City of Jerusalem, as the spiritual center for the Jewish people and the world. One can also think of the Jewish home and of the synagogue as examples of places where there is something special, a quality of holiness.
In the account of the Exodus there is another fundamental idea: the sanctification of time. This is expressed in the Divine instruction to Moses and the Jewish people that "This month shall be for you the first of the months, it will be the first month of the year." The Sages understand this as the law to sanctify the New Moon every month, and to calculate the details of the Jewish calendar.
This command is followed by the detailed description of how on the tenth of the month the Jewish people should take a lamb, and on the fourteenth of the month they should slaughter and roast it as the Paschal Lamb. That night they would go free. This would be the moment of the Exodus celebrated every year at the Seder Night in the Festival of Passover.
A key element in celebrating Passover and indeed any Jewish festival is the concept of the Jewish calendar. This runs as a lunar calendar, in which the months follow the phases of the moon. But the Jewish calendar also has to take into account the solar year, in order that Passover, in the first month, will always fall in the spring. Hence in a leap year, an extra month is added to the Jewish year.
In ancient times witnesses who had seen the New Moon would come to the Law Court in Jerusalem, and there the Sages would proclaim the start of the new month. In later generations this became difficult on account of Roman persecution. The sage Hillel II (4th century CE) therefore calculated the details of the Jewish calendar and today the entire Jewish people around the world follow his system. The unity of the Jewish calendar is a remarkable expression of the unity of the Jewish people.
The command to sanctify the New Moon and calculate the Jewish calendar was the first command given to the Jewish people as a whole. Rashi even suggests that this command might have been the beginning of the entire Torah. Through the calendar the Jewish people sanctify and transform time. Shabbat comes automatically every seven days; but the Jewish calendar, put in the hands of the leaders of the Jewish people, determines which day is the New Moon, and therefore which days are Festivals, whether Passover or Yom Kippur, the holiest day of the year.
The task of the Jewish people is to sanctify and transform existence, making it into a realm for the indwelling of the Divine. The first step in this process was the command which gave them the power to sanctify time. This was the prelude to the Exodus, which would culminate in the conquest of the Holy Land, expressing the sanctification of "place." This expresses the full role of the Jewish people: to bring holiness and light to the world in all its aspects, including both space and time.
-adapted from www.chabad.org