Abraham and the ineffable call

The revelation began formally on the day when a nomadic Semite in the neighborhood of Ur of the Chaldees heard an ineffable call and obeyed the supernatural command. What call? The call of the one God, the true God, of God. He whom the human spirit discovers, but can know only darkly, selected Abraham, son of Terah, as the messenger of his Word and ordered him to break with the errors and abominations of polytheism. We are confronted here with an essentially mystical and inexplicable fact, as mysterious in its essence and as tangible in its results as the mission of Joan of Arc, perhaps for France. How, why, in a world soaked in idolatry, did a small Bedouin clan, led by its chief, opt for the truth? The answer is obviously to be found in the will of God, already at work.

Henri Daniel-Rops, What is the Bible?