Final answer:
Augustine was asked a frivolous question about God during Book X, which related to the conflict between human freedom and God's omniscience. Augustine explained that despite God's knowledge of all things, we still have the power to choose between good and sin.
Step-by-step explanation:
During Book X, Augustine was asked a frivolous question about God which was related to the nature of time and temporality as well as agency and free will. The question revolved around how individual human freedom can be reconciled with the knowledge that God is all-powerful and knows everything. Augustine addressed this by explaining that while God knows all, it is still within our power to choose between good and sin. Only divine grace can ultimately resolve the conflict between these two wills.