The dramatic telling of the biblical story of the Exodus from Egypt is interrupted by a seemingly unrelated command, to follow a new calendar: "God said to Moses and to Aaron, 'This month shall be for you the first month – the premier one among all the months of the year'"(Exodus 12: 1-2).

Only after this command is given - the first such to the Children of Israel as a people - does God give instructions about the preparations for the first Passover meal: the slaughter and eating of a lamb on the fourteenth day of this new, first month (Aviv) and the smearing of its blood on the doorposts of the Israelites' houses. These, almost theatrical, gestures kick-start the Exodus.

Yet with all the commotion implied in this mass escape, no explanation is given for why it had to be preceded by the specific commandment about the calendar. Could not this have waited till after the Exodus? What was so urgent that this new arrangement had to be inserted right here, as though without it the Exodus itself would not have been complete or even possible?

Pesach is traditionally known as the festival of freedom, chag hacherut, since it celebrates the liberation of the Israelite slaves from Egyptian bondage. Yet this is only a part of what happened. A clue to the actual changes that the Exodus wrought might be found in the climax of the Exodus narrative, namely at Mount Sinai, where God introduces Himself by reference to the events of the previous weeks: "I am the Lord your God who brought you out of the land of Egypt, from the house of bondage; you shall have no other gods besides Me" (Exodus 20:1-3).

God defines Himself as He had never done so before, as the power that took the people of Israel out of Egypt. This becomes His signature for the rest of the Torah. Invariably, He refers to this pristine event as the way He wishes to be known. The Haggadah echoes this when it announces that the Exodus did not come by way of an angel, a seraph or a messenger but "only through the Holy One, Blessed Be He Himself".

Significantly, this exposure is not only for the Children of Israel, but for the entire world. Prior to this event who knew of God? When Moses first speaks to Pharaoh and demands the release of the Israelites, his response is one of bewilderment: "Pharaoh said: 'Who is [this] God [Adonai] that I should listen to his voice to release Israel? I don't know of any God and I won't set free the Israelites" (Exodus 5:2).

The midrashic work, The Aleph-Bet of Rabbi Akiva, depicts Pharaoh sending his wise men to search out the name of this God in his vast library, but to no avail. His response to Moses and Aaron was accordingly not some spontaneous negation but rather a well-considered reaction after the necessary research was done. Moses's own definition of God as the "God of Israel" may have even prejudged the issue. Up to that point, He was just a local tribal deity, not one to be considered in the pantheon of gods known to the Egyptians.

The story of the Exodus is the greatest public relations campaign ever mounted. When scholars discuss whether or not the Exodus is historically true, they seem to forget one thing: the question does not matter. The world believes it to be true and moreover uses it as template for radical action - political, moral and spiritual.

To put it another way, Pesach is not only a festival celebrating the freedom of the Israelites. It also signals the liberation of God; without this event the world would not have known who He was. As much as we and the world depend on Him, He, to no small degree, is dependent on us. Had we not agreed to be free, He would have remained unknown.

As it is, He revealed Himself in the world not just as its Creator, but also as one who champions liberation, who works to cast off the chains of enslavement in whatever form it manifests itself.

The introduction of the new calendar is an essential element in this whole narrative. To prove his fealty to and love for this slave people, God overturns His whole creation, and offers the Israelites a new way of perceiving time; not according to the Creation of the natural world but one rooted in the concept of freedom, individual responsibility and miracles.

It might be argued that the actual Exodus took one day, but our festival is celebrated over six more days - an echo of the six days of Creation. From behind the iron mask of time, God stretches forth His hand and offers humankind the terrifying gift of freedom.