The first book of the Confessions is devoted primarily to an analysis of Augustine's life as a child, from his infancy (which he cannot recall and must reconstruct) up through his days as a schoolboy in Thagaste (in Eastern Algeria). Wasting no time in getting to the philosophical content of his autobiography, Augustine's account of his early years leads him to reflect on human origin, will and desire, language, and memory.
[I.1-3] Augustine begins each Book of the Confessions with a prayer in praise of God, but Book I has a particularly extensive invocation. The first question raised in this invocation concerns how one can seek God without yet knowing what he is. In other words, how can we look for something if we don't know exactly what we're looking for? The imperfect answer, at least for now, is simply to have faith--if we seek God at all, he will reveal himself to us.
[I.4-6] Nonetheless, Augustine launches immediately into a highly rhetorical (and relatively brief) discussion of God's attributes. Asking God to "come into me," Augustine then questions what that phrase could possibly mean when addressed to God. The heart of this dilemma, which will turn out later to be one of the final stumbling blocks to Augustine's conversion (see Books VI and VII), is that God seems both to transcend everything and to be within everything. In either case, it doesn't make precise sense to ask him to "come into" Augustine.
God cannot be contained by what he created, so he can't "come to" Augustine in any literal sense. At the same time, God is the necessary condition for the existence of anything, so he's "within" Augustine already (so again it makes no sense to ask him to "come into me"). Further, God is not "in" everything in amounts or proportions--small pieces of the world don't have any less of God than big ones.
Having hurriedly discredited the idea of God as any sort of bounded, mobile, or divisible being, Augustine sums up for now with a deeply Neoplatonic statement on the question of "where" God is: "In filling all things, you fill them all with the whole of yourself."
Augustine then rephrases his question about God's nature, asking "who are you then, my God?" This rather direct approach generates a litany of metaphors concerning God, taken partly from scripture and partly from Augustine's own considerations. Examples include: "most high...deeply hidden yet most intimately present...you are wrathful and remain tranquil...you pay off debts, though owing nothing to anyone...." This list is rhetorical rather than analytic, and develops no coherent argument about God--it just introduces the mysteries of the subject.