That Creatures are Mutable and God Alone Immutable
17 And I viewed the other things below You, and perceived that they neither altogether are, nor altogether are not. They are, indeed, because they are from You; but are not, because they are not what You are. For that truly is which remains immutably. It is good, then, for me to cleave unto God, for if I remain not in Him, neither shall I in myself; but He, remaining in Himself, renews all things. And You are the Lord my God, since You stand not in need of my goodness.
Source: Confessions (New Advent)