In this Book Augustine assesses the nature of time itself and discusses how it relates to the eternity of God. At the beginning of the Book he tells his readers that the arguments are both intricate and difficult, and that he has to appeal for God to help. This is a rhetorical device that negates the possibility that he might be critiqued for any philosophical errors, and also serves to show that he is not philosophizing just for the sake of doing so. He is writing this with God in mind, and in an effort to further his own understanding of God. Indeed, this is true of all the Books in Confessions.
Leading from his discussion of memory, the understanding of the nature of time appears to be the next logical topic. The temporality of Earth and the eternity of God are tenets of Augustine's faith. His primary problem begins with Genesis, and the idea that God created the universe. Genesis states that God made the universe, but that suggests that there was a time before the creation of the universe. That would mean that God existed in time, and was thus limited by it.
Here, Augustine employs the figurative, or spiritual, interpretation of the Bible that was first taught to him by Bishop Ambrose. The "And God said" (Gen 1:3) passage in Genesis also presented problems for Augustine. Augustine explains that all human speech exists in time, with even a single word having a beginning and an end and "the syllables sounded and passed away." The Word could not have been like temporal speech: God's Word is always being said, and has no beginning and no end.
Another temporal word that Moses wrote in Genesis was "beginning," which caused similar problems for Augustine. Manichees were wont to question this, asking what God was doing before creation. Augustine cannot fully answer this question except to say that it is the wrong kind of question. God exists separately from time, and temporal things unfold as part of his eternal design. God decided outside of time how creation should be, and the fact that it exists in time does not mean that God exists in time. The reading of the word "beginning", as Augustine says, is not a temporal starting point, but rather the fixed point outside of time to which all temporal things can return. God is this fixed point. This response to critiques of Genesis allows Augustine to contradict the Neoplatonist notion that creation couldn't have happened, because that would have made God exist in temporality.
Augustine continues, saying that God didn't create the world at a given moment, because for God there is no time. The creation happened in a moment, and is happening eternally. The reason we cannot understand this is because human beings exist in the world, which is bound by time. God didn't start things at one point - he simply is the point at which all things begin and to which all things return. God is unchanging.
Augustine states that on earth, time is difficult to define. He writes that all creation seems to exist in time: the past, present, and future are the ways in which time is knowable to human beings. However, he argues that the past and the future, regardless of the presence of memory, do not exist: all we have is the present moment. He breaks that moment down into the smallest instance, and he cannot define what the present moment really means. This present moment cannot have space (for it is time), nor can it have duration, for once it has happened it is gone into the past. From this he posits that time doesn't truly exist, even though it seems to (because it can be discussed and measured). In this hopelessly negative argument, Augustine accepts that the notions of past, present, and future are useful for human beings.
He refutes the idea that time can be measured through the movement of stars and planets. He points out that they may move in time, but that those heavenly bodies are not actually time. Even if none of the stars or planets existed, time would still pass. Augustine cannot give the reader a positive definition of time - he offers only a negative one. He suggests that, as Plotinus writes, time is actually a distention of the soul. He adds that this is a distention away from the perfect being of God.
In an about-face, Augustine suggests the possibility that time is something that we measure within our own memory. We cannot grasp the past (for it has no existence), but we can consider the memories of the images or sensations we had in the past. Time is thus not a feature or property of the world, but a property of the mind.
This criticism of the beginning of Genesis, which is also referred to in other parts of Confessions, was common amongst Manichees and other Christians in Augustine's day. This discussion of time in the rigorous philosophical sense may seem out of place in a theological text. In fact, Augustine apologizes somewhat at the beginning of this Book for the philosophical nature of this discussion. He does not want to appear to be philosophizing for vanity or curiosity's sake (he considers idle curiosity a sin; see Books II and III). On the surface this discussion may seem like secular philosophizing, but, especially in light of the preceding Book and Augustine's ongoing difficulties with the Biblical book of Genesis, the understanding of nature of time is necessary to defending the nature of the omnipotent, unchanging God of Catholicism.
Many of the points in this chapter seem either unknowable or pointless even to the modern metaphysical philosopher. In Augustine's day, however, these ideas were of the utmost importance to religion. It was a time of many different types of heresy (Manichaeism, Donatism, Arianism, Gnosticism, among others), most of which differed with each other specifically with regards to the nature of God and Jesus Christ. Definitions of things like creation and time were integral to the explanation of the nature of God, so these sometimes arcane arguments were of the highest dogmatic necessity.
The Catholic Church at this time was not only defending its dogma from heresies, but was also in the process of codifying it completely and writing it down. Things like baptism and some kinds of sin were thought of slightly differently in the Catholic Church of Augustine's day, partially because questions like these were not completely codified. This kind of theological inquiry, especially from someone of Augustine's education and theological genius, was necessary and very valuable to the early church.
The refutation of the existence of time is persuasive even today. The idea that God is the "beginning point" rather than the beginning in a temporal sense is particularly neat, though Augustine, as in so many things, owes a debt of gratitude to the Neoplatonists for this concept. Despite the muddled and convoluted form Augustine's arguments sometimes take, these arguments are useful not only to metaphysical philosophers, but to anyone who has ever pondered the first principles. Augustine is rigorous in that he takes nothing, not even the Bible, on pure faith. In true skeptical fashion, he is willing to question everything, and is determined to try to get to the base of any philosophical problem, no matter how remote or difficult.