Pentecost, or Feast of Weeks, is the conclusion of Passover that took place seven weeks earlier. The two holidays are connected via the Counting of the Omer which started on the second day of Passover. The counting of 49 days represents the preparation and anticipation for the giving of the Torah, that, according to Jewish tradition, was given on Pentecost.
Following this line of thought, on Passover the people of Israel were freed from the bondage of the Egyptian slavery hence, from the physical aspect of slavery. On Pentecost, with the giving of the Torah, the people of Israel were made free from the bondage of the natural laws through obedience to the divine commandments which are in the Torah.
This percieved contradiction of law and freedom baffles Christians, many of whom have been trained to think of the Law as enslaving rather than making one free. Secular Jews also tend to think along these lines. For them the Torah takes away the freedom to live as one wishes.
But from the long-held Jewish perspective, the Pentecost marks a joyous event in which the people of Israel agreed to accept the Torah, something that shouldn't be taken for granted, given the natural reaction to the many laws that, as stated, seemingly restricts rather than extends freedom.
The contradiction between Law and freedom has occupied Jewish sages from time immemorial, and their conclusions are profound. Commenting on the physical aspect of the divine Tablets as described in Exodus 32:16 – "the tablets were God’s work, and the writing was God’s writing engraved on the tablets" – the Talmudic sage rabbi Joshua son of Levi takes advantage of the Hebrew language, and slightly changes the vowels of "engraved" to reach the conclusion that one should read "freedom" - (herut instead of harut). "Freedom on the tablets" thus have become the way in which Jews view the commandments.
How the commandments make one free was explained by the renowned scholar Yeshayahu Leibowitz, in his 1953 article, "Practical Commandments." Human beings, he reasons, can't escape the laws of nature. This means that man is bound to the "causal chain of forces … which act upon him and within him." The natural man is enslaved to the natural laws, and as such is "just like the cattle grazing in the pasture, which are also free from the Torah and Commandments; that is, from any law externally imposed.” This bondage includes will and reason. The conclusion, then, is that for man to be truly free, he must have external, divine, forces working within him; forces that are provided through the commandments.
From this perspective, for Jews to be free from their beastly nature, they must accept other laws than human laws in order to transcend nature. Israel is therefore, since the giving of the Law are under a divine unnatural law, that has the external power to elevate them to a higher state that can make them a light to the world.