Abram took Sarai his wife and his nephew Lot, and all their wealth that they had amassed, and the people they had acquired in Charan; and they embarked for the land of Canuan, and they came to the land of Canaan (Bereishis 12:5).

They brought them under the wings of the Divine Presence. Avraham converted the men, and Sarah converted the women (Rash) to Bereishis 12 5).

World history, Chazal tell us, is divided into three periods, each lasting two thousand years. The first is called the era of tobu vavobu (void and nothingness), the second the era of Torah, and the third the Messianic Era. Chazal identify the beginning of the era of Torah with Avraham's conversion of the idol worshipers of Charan into believers in God.

The question arises Why did Chazal view this event as ushering in the era of Torah? After all, the Torah pre-existed Creation and was the blueprint for Creation. Adam and Noach learned Torah long before Avraham was born, and Shem and Ever even set up a yeshivah.

In order to answer this question, we must first understand Avraham's unique role in the transmission of knowledge of Hashem. Raavad (to Hilchos Avodah Zarah 1 3) asks why Avraham alone of all the righteous people of his generation and the preceding ten generations is credited with influencing the masses. Surely the others also protested against idolatry and rebuked their wayward contemporaries. He answers that while the other tzaddikim admonished their contemporaries, they were not able to break the idols because the idol worshipers hid them. Only Avraham was able to find the idols.

Raavad's words are difficult to understand. Was Avraham Avinu, then, only a better detective than the other tzaddikim, and thus able to ferret out the hidden idols? Moreover, what does Raavad mean that they hid their idols? Nimrod and his cohorts publicly worshiped idols and idol manufacturers, like Avraham's father, carried on a brisk, open trade.

To understand Raavad we need a deeper understanding of ancient idolatry. Rambam explains that the original idol worship was a well intentioned mistake. Just as one honors the king by honoring his emissaries, so did the generation of Enosh worship various natural phenomena, which God had invested with certain powers, as a means of honoring the Creator of those phenomenon. Their mistake lay in failing to recognize that showing respect to the king's emissary is only a form of honoring the king when he is absent. But when he is present, it is tantamount to rebellion. Since Hashem is always present, the worship of His creations is always a diminution of Him: Don't accept any other powers in My presence" (Devarim 5:7).

The two thousand year period preceding the era of Torah is described as tobu vavobu-an era of confusion, of light and dark mixed together and not easily delineated one from the other. With the sin of Adam, the relative terms good and evil, replaced the absolutes of truth and falsehood. The various shades of good and evil became a confusing admixture.

The Torah, by contrast, distinguishes absolutely between pure and impure, light and darkness, life and death "Behold I have placed before you today life and good, and death and evil" (Devarim 30:15). Only the Torah allows us to separate the light from darkness, to perceive good as absolute truth and evil as absolute falsehood.

The confusion introduced by Adam's sin became the principal tool of the yetzer hara (evil inclination). As the Baal Shem Tov explains, the Satan will be held culpable in the future not for attempting to seduce man into sin-that is his function-but rather for making the sin appear as a mitzvah. Thus we tell ourselves when we sleep late and miss davening with a minyan that our sleep is a mitzvah and our intention is only to learn Torah with a clearer head that day. This is the tobu vavobu of the yetzer hara. Torah is the remedy.

The idol worshipers of Avraham's generation did not hide their idolatry physically, but spiritually. They masked it as righteousness and honor to God. They created ideologies to cloak their sins in light and virtue. Prior to Avraham no one was able to expose the sham, to delineate the light and darkness. This failure prevented them from exercising any lasting influence on those they admonished. They could not break the idols.

Only Avraham saw the light and darkness in their true perspective and conveyed this to the masses. He exposed evil for what it was and thereby transformed the idol worshipers into believers in God. Avraham's life work, then, was the beginning of the era of Torah, the delineation of light and darkness.

Since Avraham's unique ability was to distinguish between light and darkness, he could welcome into his house wanderers who bowed to the dust of their feet, yet found it necessary to distance himself from his nephew Lot. His very resemblance to Lot made it imperative that he separate himself so as not to confuse his true righteousness with Lot's apparent righteousness. "Separate yourself from me," Avraham told Lot, "for we are brothers." Rashi explains the term "brothers"-"They looked alike."

Lot was the personification of tobu vavobu. On the one hand, he appeared to be righteous like Avraham he baked matzos and invited in guests, even at risk to himself. But, in fact, the jumble of darkness pervaded his life he chose to live among the wicked people of Sodom, lured by the wealth he saw there. Lot's admixture of good and evil represented the antithesis of Avraham's mission in this world. Hence, Avraham had to separate from him.

Of all the non-kosher animals, the pig has always symbolized impurity for the Jewish people precisely because it bears the external sign of a kosher animal, cloven feet. It is the kosher feet that make it the most loathsome of the non-kosher animals. So, too, the most dangerous ideologies are those that succeed in garbing themselves in an aura of piety and righteousness, that claim the mantle of Torah and authentic Judaism, but are in essence total distortions of the Torah.

As descendants of Avraham, who introduced the era of Torah, it is our task to toil in Torah to discern truth from falsehood, light from darkness, the holy from the profane.