The best way to understand the logic behind an ex-nihilo universe is to use an analogy. Just as zero is the sum of all positive and negative numbers, nothing is the sum of everything positive and negative. It sounds absurd but nothing is, in reality, everything. This means that all properties/things must come in complementary/opposite pairs so as to sum up to nothing. It follows that any imbalance (a non-zero sum) must be corrected so as to conserve nothing. Change/motion is thus nature's way of correcting a violation of the mother of all conservation principles, the conservation of nothing. This law is applied universally, i.e., non-locally. The universe is one, as its name implies.