What does it mean to be human? This is one of philosophy’s oldest questions, and few thinkers have tackled it with as much depth and theological rigor as Saint Augustine of Hippo (354-430 CE). His answer was neither purely materialist nor simply dualist. For Augustine, the human being is defined by the union of a rational soul and a body – a unity in which the soul holds primacy, yet the body is never dismissed. Understanding his position requires us to move through three core ideas: what the human being is composed of, what makes the rational soul distinct, and how humanity fits within a divine hierarchy that places God above all else.
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A unity of soul and body – not a simple division
Augustine begins from the premise that a human being is not just a soul trapped inside a body, nor merely a biological organism. According to the Stanford Encyclopedia of Philosophy, Augustine holds that the human being is a compound of body and soul, where the soul – conceived as the life-giving element and the center of consciousness, perception, and thought – is the ruling part. But ruling does not mean the body is irrelevant. The body is the vehicle through which we perceive the world, act within it, and express our rational and moral life.
This position set Augustine apart from certain strands of ancient thought. The older Platonic tradition had treated the body as a kind of prison for the soul – the soma as sema (body as tomb). As the scholar Peter Brown’s tradition of Augustinian study notes, this inheritance passed into early Christian thought somewhat uncritically, and the young Augustine was himself influenced by it. However, his mature philosophy rejected this radical separation. Writing in the Homiletic & Pastoral Review, philosopher Br. Justin Hannegan traces how Augustine eventually moved from identifying man with the soul alone to articulating a more integrated definition: man is a rational substance consisting of soul and body together. The doctrinal reason was significant – identifying the person exclusively with the soul would have undermined the Christian teaching of the Incarnation, in which Christ’s identity necessarily included his body.
Augustine’s own words in De Trinitate and In Iohannis evangelium tractatus reflect this mature position: a human being is “a rational soul with a body,” and as Philosopher Kings summarizes, “neither would the body be a man if the soul did not exist, nor in turn would the soul be a man if a body were not animated by it.” The two are distinct, but neither is fully human alone.
Why Augustine rejected materialism
Before arriving at his mature position, Augustine himself went through a materialist phase. Hannegan documents that in his early years, Augustine believed the soul to be a fine material substance dispersed throughout the body – he simply could not accept any substance that lacked spatial extension. This is a recognizably empiricist instinct: if something cannot be measured or located in space, it seems like nothing at all.
What changed his mind was his encounter with the philosopher Plotinus and the Neo-Platonic tradition. Reading Plotinus convinced Augustine that God is an immaterial substance, and from this he reasoned that the human soul – created in God’s image – must also be immaterial. He then developed a series of philosophical arguments to support this. Three of these arguments stand out: first, the soul’s objects of cognition are not spatially limited, so the soul itself cannot be a material body; second, a material body cannot think or will, but the soul clearly does; third, we attribute moral qualities such as justice to the soul, and moral qualities cannot be three-dimensional properties of physical matter. Therefore, the soul cannot be material.
This was a decisive break with any view that reduced human beings to their physical components. For Augustine, reducing the human person to matter alone could not account for conscience, rational deliberation, or the moral life – the very things that make us distinctly human.
The rational soul: what defines humanity
At the center of Augustine’s concept of the human being is the rational soul. It is this soul that distinguishes humans from plants, which have only vegetative life, and from animals, which have sensitive but not fully rational souls. Augustine describes the soul as “a certain substance partaking in reason and suited to rule the body.” It is through the soul that we reason, exercise free will, form moral judgments, and – crucially – relate to God.
In his work De quantitate animae (On the Greatness of the Soul), Augustine argues broadly that the soul’s greatness refers not to spatial extension but to its vivifying, perceptive, rational, and contemplative powers – powers that enable it to draw close to God and that presuppose immateriality. The soul is great not because it is large, but because of what it can do and what it can know.
The rational soul is also the seat of the imago Dei – the image of God in humanity. A study published in the journal HTS Teologiese Studies explains that for Augustine, the image of God in humanity is located in the rational or intellectual soul, composed in a Trinitarian structure of memory, understanding, and will – a reflection of the three persons of the Trinity. The St Andrews Encyclopaedia of Theology confirms that this ‘trinity’ within the rational soul serves as the means by which humans know God, and it is indelible – present even in a state of sin. The body, by contrast, bears only a “trace” (vestigium) of God, not the image itself.
This is why the rational soul carries such philosophical weight in Augustine’s account of the human being. It is not merely the organ of thought; it is the part of us most directly oriented toward the divine.
The soul’s hierarchy: above matter, below God
Augustine’s concept of human nature does not exist in isolation – it is embedded in a larger cosmic hierarchy. At the summit is God, then angels, then rational souls, then the material world. This ordering is not arbitrary; it reflects the degree to which each level of reality participates in being, truth, and goodness.
The rational soul occupies a uniquely intermediate position. It is superior to all material things – it cannot be measured in space, it can grasp eternal truths, and it governs the body as a rider governs a horse. Augustine uses precisely this comparison, describing the soul as steering the more animalistic instincts of the body and guiding a person along a course of rational and moral action. Yet the soul is also definitively inferior to God. It is a created substance, not a self-sustaining one. Its rationality and moral capacity are real, but they depend on divine illumination for their proper functioning.
This is where Augustine diverges sharply from a purely Platonic framework. For Plato, the soul’s ascent is primarily an intellectual achievement – the philosopher rises through reason to contemplate eternal Forms. For Augustine, the soul’s relationship with God cannot be secured by reason alone. As Western Kentucky University’s survey of Augustine notes, humans are constantly drawn toward excessive satisfaction of lower desires for material things, and this pull – which Augustine traces to inherited original sin – means that the rational soul needs divine grace to align its will with God. Reason is necessary but not sufficient.
The body plays its own role in this hierarchy. Augustine compared it to the physical frame of a lantern, carrying the flame of the soul. It enabled humans to interact with the physical world, to learn through the senses, and to fulfill the command to procreate and to live in community. The body is not evil – it is created by God and therefore good. But its desires and vulnerabilities must be governed by the rational soul, not the other way around.
The soul’s immortality and divine origin
A further dimension of Augustine’s account is his insistence on the immortality of the soul. The Stanford Encyclopedia notes that as late as De Trinitate, Augustine endorses the Platonic axiom that the soul is by nature immortal and that its immortality can in principle be demonstrated philosophically. One classical argument runs like this: the soul is the seat of eternal truths; that which contains eternal truths cannot perish; therefore the soul is immortal. Augustine also draws on the Christian teaching of resurrection – not just the soul’s survival, but the eventual reunification of soul and body in glorified form.
A detailed theological study clarifies that for Augustine, immortality in the fullest sense belongs properly to God alone. The soul’s immortality is not self-derived – it is sustained by its participation in God. This is an important nuance: the soul does not simply survive death because of its own power; it persists because of its relationship to the divine source from which it came. Immortality, for Augustine, increasingly meant not mere persistence but a restored and elevated participation in God – an eschatological transformation of the entire human person, body and soul alike.
A dissertation from Southern Baptist Theological Seminary summarizes this well: Augustine’s conceptualization of the soul is intricately linked to Scripture and tradition, and encompasses the soul’s creation by God, its anthropology, its spiritual growth, and its eventual reunification with the resurrected body. The soul’s journey is not complete until the whole person – rational soul and renewed body – stands in the presence of God.
Augustine between materialism and dualism
It is worth pausing to appreciate the precision of Augustine’s philosophical position. He is not a materialist – he explicitly argues against reducing the human person to physical processes. But he is also not a straightforward dualist in the Platonic sense, since he insists that the body is genuinely part of what constitutes a human being, not a mere instrument or prison. His mature definition – that man is a rational substance consisting of soul and body – according to Hannegan’s analysis, replaced both the Neo-Platonic tendency to identify man with the soul alone and any view that collapsed human identity into biological matter.
This position has proven remarkably durable. The Catechism of the Catholic Church (n. 362) still reflects Augustine’s framework in describing the human person as a unity of body and soul. Contemporary debates in philosophy of mind about the relationship between consciousness, cognition, and the physical brain echo the very problems Augustine was wrestling with in the fourth and fifth centuries: how can an immaterial, rational capacity be so intimately bound to a material organism? Augustine’s answer – that the soul governs the body through a relationship of power rather than spatial mixture – does not resolve every puzzle, but it frames the question in a way that has shaped centuries of philosophical and theological reflection.
What do you think? If the soul’s primary function is to govern the body through reason, what happens when rational capacity is compromised – does that change a person’s fundamental human status in Augustine’s framework? And does Augustine’s insistence that the body is genuinely part of human identity make his view more or less compelling than a purely spiritual account of what we are?
References
- https://plato.stanford.edu/entries/augustine/
- https://www.gruparibau.com/st-augustine-soul-and-immortality/
- https://www.hprweb.com/2015/08/how-augustine-made-us-more-than-matter-and-immortal/
- http://www.philosopherkings.co.uk/augustineonhumannature.html
- https://scielo.org.za/scielo.php?script=sci_arttext&pid=S1017-04992016000100014
- https://www.saet.ac.uk/Christianity/ImageofGod
- https://people.wku.edu/jan.garrett/august.htm
- https://repository.sbts.edu/handle/10392/7236
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