Final answer:
Augustine believes that Heaven and Earth's existence confirms they were created because they cannot be self-originating; instead, they require a creator. Everything in the material world is contingent and cannot exist without a necessary being, such as God, to bring it into existence.
Step-by-step explanation:
Saint Augustine argues that the mere existence of Heaven and Earth is evidence that they were created, as opposed to having created themselves. This idea stems from a fundamental theological principle that everything that exists is contingent on a creator. Augustine's theological framework deems the existence of Heaven and Earth to be good by the virtue of them being God's creations. Since they are creations, they cannot be self-originating.
According to Augustine, all of creation exists by the will and design of an intelligent and necessary entity, which is God. As the supreme creator, God is responsible for all that is seen and unseen, and this very existence is both a testament and proof of God's own nature as the uncreated creator. An argument Augustine uses is related to the concept of contingency, asserting that the material world, including Heaven and Earth, changes and depends on something else for its existence, therefore it could not exist on its own without a necessary being bringing it into existence.