What is Holiness?
Leviticus 19:2 describes God commanding: “You must be holy, for I, the Lord your God, am holy.” What is God demanding? While most people think holiness is a special quality they need to add to their behavior, modern scholars accept the ancient understanding in Midrash Sifra that holy (kodesh) means “separate.” The passage is saying, “Just as I, God, am separate, so must you be separate.”
The Bible commentator Sforno understood the mandate in a positive way. It requires people to emulate God to the best of their ability. This concept is called Imitatio Dei; Latin words because this concept was accepted as proper by Christianity. It requires people to attempt to be merciful, gracious, kind, righteous, just, and all the other attributes that people ascribe to God.
Maimonides and Nachmanides interpret this verse in still another way. The two scholars recognize that humans have different abilities in understanding. This required the Torah to command a lower level of behavior frequently, although it often suggests ways that a person with more intellect can understand the matter and act in a higher level.
Maimonides applies this concept of going beyond the rules for the general population to his teaching of the “golden mean.” The average person should take the middle path between the two extremes of excessiveness and avoidance. This is an easy rule to follow, but intelligent people should use their intelligence to make decisions, which frequently requires them to do less or more than the “golden mean.”
While the Midrash defines “holy” as “separate,” it does not mean practicing asceticism. One has only to look at the entire chapter 19 of Leviticus to see that it not only mandates holiness, but informs us how to become holy. It contains the golden rule, commands a form of taxation to help the poor, prohibits stealing and dealing deceitfully and lying, advocates treating a laborer fairly, not cursing the deaf, nor placing a stumbling block before the blind, among many other social laws. Holiness means being separate, different than the bulk of humankind.
Maimonides writes that the purpose of the Torah laws is threefold: to promote the understanding of true ideas, and to improve individuals and society. He views the story in Genesis of Jacob’s dream of a ladder, where angels ascended and descended on it, as a metaphor. People should ascend to gain knowledge and then descend to use that knowledge to help other people.
 I explain this concept in detail – a concept understood and used by many ancient philosophers – in my book “Rational religion,” which I wrote under the pseudonym Daniel A. Diamond.
 Friedrich Nietzsche called such a person a great individual, a “superman.”