“There was once a Cossack who saw a rabbi walking through the town square nearly every day at about the same time. One day he asked curiously: “Where are you going, rabbi?” The rabbi answered: “I am not sure.” “You pass this way every day at this time. Surely, you know where you’re going.” When the rabbi insisted that he did not know, the Cossack became irritated, then suspicious, and finally took the rabbi to jail. Just as he was locking the cell, the rabbi faced him and said gently: “You see, I didn’t know.” Before the Cossack interrupted him, the rabbi knew where he was going, but afterward, he no longer knew. The interruption (we can call it a measurement) offered new possibilities. This is the message of quantum mechanics. The world is not determined by initial conditions, once and for all. Every event of measurement is potentially creative and may open new possibilities.”