Aquinas introduces this question with a brief road-map that covers much of the rest of the first part of the summa. Questions 50-64 are to be devoted to purely spiritual creatures (the so-called “Treatise on the Angels”), Questions 65-74 to the purely corporeal elements of creation (the so-called “Treatise on the Six Days”), and Questions 75-102 are devoted to those creatures that include both spiritual and corporeal elements in their being (the so-called “Treatise on Man”). If we refer back to the introduction to Ia.q44 (at the start of the Treatise on Creation), we see that Aquinas is leading us through the different types of being created by God. The very final part of the first part of the summa, from Ia.q103 onwards, will be devoted to the governance of creation; that is, the relationship between God and the created order.
In this, the “Treatise on the Angels”, Aquinas will consider created beings that are purely spiritual. He will describe their substance (in Questions 50-53), their intellect (Questions 54-58), their will (Questions 59-60), and their creation (Questions 61-64).
Why this Question Matters.
It is a doctrine of the Christian faith that the beings called “angels” exist. But the sources of revelation about the nature of these angels is quite scanty: we know quite a lot about their function (the word “angel” derives from the word in Greek meaning “messenger”), but very little about what they are. Aquinas has built up a coherent metaphysical framework of being that allows us to talk about God and about material things; it is now time for him to describe how non-material but created things might fit into this framework.
The Thread of the Argument
A1: From a modern point of view, the idea of the existence of Angels seems a very strange thing. Their existence is attested to in the sources of Christian revelation and is therefore a truth of the faith in the Christian religion. However, one might ask whether the existence of the Angels is purely a truth of faith or whether there are any other grounds that might justify belief in their existence; for example a demonstration based in natural theology. Of course, we must also ask what these angels are supposed to be: what is their quiddity? Aquinas starts the “Treatise on the Angels” from the point of view of the necessity of the existence of incorporeal creatures; as such this section of the summa fits into a wider inquiry into what is included in the whole of creation. Aquinas argues that the existence of incorporeal creatures is necessary because God has created creatures principally for their assimilation to God; they come out from God and return to God. Perfect assimilation of an effect (a creature) to its cause (God) occurs when the effect imitates the cause with respect to the way that the cause creates the effect. As God creates the universe through his intellect and will (Ia.q14.a8 and Ia.q19.a4), the perfection of the universe requires there to be purely intellectual creatures. As an act of the intellect is not the act of a body or of a corporeal power, there must be purely incorporeal beings.
A2: Having disposed of the question of whether angels could be corporeal, it might seem odd that Aquinas now asks whether angels are composed of matter and form, for this latter would seem to imply that they are corporeal. The point is that Aquinas is addressing theories current in his time (especially among Franciscan theologians) that there might be some sort of matter-form composition in angels even if it isn’t the same sort of matter-form composition that exists in everyday objects. Aquinas traces the roots of some of this current thinking back to the Jewish philosopher Avicebron, who flourished in the eleventh century. According to this theory, a sort of “cosmic matter” becomes specialized to “corporeal matter” in bodies and “spiritual matter” in spiritual beings in composition with their respective forms. Aquinas rejects this idea, pointing out that it stretches credibility to try to make this consistent with intimate connection between matter and the notion of quantity. Moreover, Aquinas insists that the very nature of spiritual beings is that they are purely intellectual and that therefore, because of the nature of the intellect, they cannot admit of any composition with matter. Aquinas will return to the theme of the essential non-materiality of the intellect in Ia.q75.a5, but the argument boils down to the fact that if matter was essentially involved in the operation of the intellect then the reception of forms in the intellect would involve the composition of that form with matter, created a new individualized version of what is comprehended.
There are still some troublesome objections to be met. The matter-form composition gives us the genus and difference that allow us to distinguish things within a genus; without the matter-form composition we seem unable to make such distinctions. Aquinas argues that we cannot carry over so easily what we know about material objects to the spiritual world. In the spiritual world there is no correspondence to the material distinction between the determined and the determining; rather, each being of itself occupies a distinct degree in the scale of being. This will lead Aquinas to argue in article 4 that each individual angel occupies its own species within the genus “angel”.
Perhaps more troubling is that in material things the composition of matter and form corresponds to the actualizing of potentiality of matter by form. It would seem that without this composition a spiritual being must be considered pure act and not limited by matter and therefore infinite. Spiritual beings are beginning to sound a bit too much like God Himself for comfort! Aquinas points out that the composition of matter and form is not the only composition that must be considered when we think about actuality and potentiality: there is also the composition of essence and existence. It is this composition of “that which” and “that by which”, held in being by God, that distinguishes the pure actuality of God from the high-but-not-pure actuality of the angels.
Similarly this composition of essence and existence limits the spiritual creature to be a particular being and thus, absolutely speaking, limits it to be finite. But, as Aquinas points out in the spirit of the neo-Platonic liber de causis, we might consider such spiritual beings to be “quasi-infinite”. To illustrate what this means, he considers the example of “whiteness”; if whiteness could subsist on its own it would be non-finite inasmuch as it would not be limited to being this-particular-whiteness in this particular object. However, it would still be finite, absolutely speaking, as its being is that of a particular determinate type of thing. So, if we looked “from above”, from God’s point of view, purely spiritual beings would be determinate finite beings. If we look “from below”, such pure forms have a certain sort of infinitude.
A3: How many angels are there; only a few or many? After reviewing the approaches of Plato, Aristotle and Maimonides to this question, Aquinas comes down on the side of “many”. Not only does scripture appear to support this position, but one might argue that God would produce more things of a more perfect nature in creation. In the spiritual world such plenitude is represented by number rather than extent, so we may infer that the number of the angels far exceeds the number of material things.
A4: If we think about how angels might differ one from another, we might consider that any differences that they do have are differences of degree rather than of kind. Aquinas, however, disagrees: each angel occupies its own species in the genus of “angel”. This follows from the argument of article 2 that there is no composition of matter and form in angels. Because matter is the principle of individuation of things there can be no individuation of angels within a species. Each angel fully realizes the actuality of what its essence can be; that is, the composition of essence with existence fully determines what the angel is, there is no alternative determination of the angel.
Aquinas gives a helpful analogy carried over from article 2: if we consider “whiteness” purely as a form, it makes little sense to talk about different “whitenesses” as forms as opposed to different realizations of whiteness in things. When we say that the whiteness of this object differs from the whiteness of that object, we are simply saying that the form “whiteness” is realized differently in the two objects, not that there are two different “whitenesses”. “Whiteness” is multiplied by being instantiated in different matter; this is not something open to the essence of an angel.
A5: Aquinas has argued that angels are not a composition of form and matter but are a composition of essence and existence. It follows from this that angels are naturally immortal. What this means is that once an angel has been brought into existence its nature is such that it will not, by the course of nature, perish. This does not mean that an angel is a necessary being in the way that God is a necessary being; an angel’s continued existence depends on the First cause maintaining the composition of essence and existence in it.
Aquinas argues for this position by observing that things perish by the separation of their form from their matter. If we think about non-human material objects, we observe that a matter-form composite not only has potentialities to lose and gain accidental forms but it also retains the potentiality to lose its current substantial form and gain a new substantial form. So, a duck can not only lose its current plumage and gain a new one (whilst still remaining a duck) but it can cease to be a duck and become a duck-corpse. (More strictly, the matter of the duck is at first informed by the form of a duck and is then informed by the form a duck-corpse). It appears to be an inherent feature of matter-form composites that they have a potentiality for the eduction of a new substantial form: within them lie the seeds of their own destruction. When we turn to the consideration of angels, we observe that they have no matter, therefore they cannot perish in this way: they can only cease to be by God ceasing to cause their essence-existence composition. We might even say that they are naturally immortal and supernaturally mortal!
- As God creates the universe by means of his intellect and will, it is fitting to the perfection of that universe that there be purely incorporeal spiritual creatures as part of that creation.
- As angels are purely intellectual creatures, there is no composition of matter and form in then, rather only a composition of essence and existence.
- There are many more angels than there are material objects.
- Each angel is unique to a species.
- Angels are not a composition of matter and form and therefore they are naturally immortal. The only way that an angel can cease to exist is by God withdrawing the cause that maintains their composition of essence and existence.
- Although it may seem at times that Aquinas’s treatment of the angels is ad hoc, simply trying to fit the data of revelation, it might better be seen in more principled terms than that. Aquinas has identified various compositions that underlie the being of things: matter-form, essence-existence, and actuality-potentiality. Having identified that it makes good metaphysical sense to talk about a being (God) that is pure actuality and in which there is no composition of essence and existence or of matter and form, it would seem perfectly reasonable to investigate whether there can be beings that are compositions of essence and existence but not of matter and form.
- Having talked about the natural immortality of the angels, one is immediately drawn to the question of the immortality of the human soul. We have already observed that for non-human material objects, the composition of matter and form can go out of existence and that the forms of such things go out of existence with the material object. Yet for the angels, there is a natural immortality because there is no such matter-form composition. The intellectuality of the form of an angel demands its non-materiality and it is in this intellectuality that its subsistence, the seed of its natural immortality, lies. When we turn to human beings we are met with a mixture: we are composites of matter and form and yet we also possess an intellect. As such we perish but our form, being an intellectual form, must continue in being. Aquinas will return to this issue in Ia.q75.