When Avraham is told to leave his country, he’s being told to leave behind more than a mere place. The midrash sees God’s command to Avraham as a lesson in self-transformation. Avram and Sarai cannot give birth to children; Avraham and Sarah will give birth to a nation!
It’s been said that the first chapter of B’reishit (Genesis) contains polemics against just about every worldview common in the ancient world. One of those worldviews is the notion of destiny, that a person’s fate is written in the stars. B’reishit puts the emphasis from the very beginning on human free will.