Every person is born underneath an astrological field, a particular energy-flow that determines many specifics of life – personality, circumstances, potential. Now in Hebrew this is called "mazel" – literally an alignment of stars. But it can also mean "luck," as when we wish someone Mazel Tov.
A person's mazel is pre-programmed from birth. But in Parshat Lech Lecha, God takes Abraham outside and tells him to "see if you can count the stars." God changed Abraham's name and metaphorically lifted him above the stars to re-align his destiny.
Why did Abraham merit this special treatment? At the time, the prevailing world system was idolatry. Abraham saw the falsity of this idea, and lifted himself above societal norms. For this act of transcendence, God responded in kind by lifting Abraham out of the natural system – "above the stars."
This established a principle for all eternity – that the Jewish people are above "mazel." We need not accept the "fate of the stars." And surely, history bears this out: The Jewish people have outlasted all the great empires like the Greeks and Romans. And even in our lifetime Jews in Israel have defied all odds by thriving in a land surrounded by enemies.
But beyond a national level, this idea also has powerful application to our personal lives. The Talmud tells us that the daughter of Rebbe Akiva was destined to die on her wedding day. At the wedding meal, the bride absentmindedly stuck her hairpin into the wall behind her – unknowingly killing a cobra that was prepared to strike. Later, when they found the dead cobra and realized the bride's good fortune, they asked her to recall the day's events. She reported that in the midst of the wedding festivities, she had noticed some poor people outside, and she'd left her own wedding in order to bring them food. An incredible act of humanity!
So here we see the principle in action: This woman's super-human act raised herself out of the pre-set system – changing her destiny and saving her life. If we aspire, we can do it, too.