Essence and Existence: The Problem of the One and the Many

Reading Time: 6 minutes

By Jonathan C. McMonigal, Holy Apostles College and Seminary

Part I: Introduction

When searching to explain the metaphysical structure of reality, the mind encounters the problem of the one and the many. There are various things that inhabit our experiential world, yet they dynamically change over time. This begs the question of whether reality rests upon an immutable foundation or if all is perpetual change. The one and the many cannot be illusions of the mind, since the mind experiences the reality of both. Instead an explanation must account for the real unity of the universe and the diversity of the things which inhabit it. The quest of the mind is to discover the answer behind the infinite one and the finite many. Now metaphysical investigation renders an answer to this problem in what is colloquially called classical theism, namely the proposition that God is necessarily the ultimate cause of all being.

From the Neo-Platonists of antiquity to the Neo-Scholastics of today, the diversity and unicity of experienced reality is explained by God. This hypothesis is metaphysically anchored in an absolute simplicity of the divine. The subjective experience of each philosopher is an objective world of various compositions, and this unfathomable expanse of multiplicity must be grounded in a shared principle of unicity. These various things go by the name of essences, and they are all really distinct yet grounded in the same shared existence. The compound of essence and existence cannot go on into infinitude, lest a chain of causation be without a logical beginning. The origin of the many must originate from the one, and the essence of the one must avoid this problem of the compounded many. The one must not be a static object, since the causal chain of the compositions must originate from a principle of agency. The problem of the one and the many is answered by the distinction of essence and existence, the composition of creatures, and the absolute simplicity of God.

Part II: The Distinction of Essence and Existence

Before an exploration of God proper, techinical definitions of the terms existence and essence are necessary as first principles. Now metaphysics is traditionally defined as “…the study of being as such…”[1] The term being is connected with that of existence, because “being means that-which-has-existence-in-act”.[2] To be is to exist, and vice versa. A difference between existence in act versus existence in potency is this: the former exists in reality while the latter only exists in limbo. Existence is necessarily predicated upon an actual being, because it cannot be found in the void. To phrase it in metaphor: “being is that which is actually present in some way, presents itself as standing out from the darkness of non-being into the light of being.”[3] Thus existence is to be a thing standing forth from the void.

If existence deals with the reality of a thing, then essence deals with what is the reality of said thing. To be more precise, essence is defined as such: “that which makes a being to be what it is, i.e., this particular being distinct from every other.”[4] Since existence must be predicated upon real things, said things must possess marks of differentiation. Sense experience informs the mind to the diverse essences of things. As St. Thomas Aquinas remarks: “the essence…connotes only what is included in the definition…[5] To comprehend existence is to encounter the essences. Existence can only be known through essence, and as it is said: “a thing is intelligible only by its definition and essence.”[6] Thus existence and essence are necessarily bound together.

Part III: The Composition of Creatures

Since the concepts of existence and essence have been defined in the abstract, they must now be considered in the concrete. Creatures are to be defined as compositions consisting of both existence and essence. They must consist as such: “(1) an act of existence, by which it actually exists, is actively present in the universe of real beings; and (2) a limiting essence, by which it exists in this or that particular mode or manner of existing, as this or that particular being and not some other.”[7] Now existence must be one while essence can be diverse, because there is only a binary option whether something is real or not. The mode of existence is open to diversity, for as it is said: “…a stone’s act of existence is other than that of a man.”[8] The composition of creatures is found in that they are simultaneously similar in existence yet dissimilar in essence.

Turning from the object to the subject, human experience is unique in reality in so much that man is conscious of his own composition. The human mind is aware of the subjective contingency of existence. As it is said: “Moreover, every composite, precisely as composite is potentially dissolved, although in certain things something is present that resists dissolution.”[9] Man knows that he actually began to exist, so also he knows that he potentially can cease to exist. The fact that essences are potentially capable of creation or annihilation implies an immutable source of existence. As it is said: “Therefore that thing, whose existence differs from its essence, must have its existence caused by another.”[10] Reflection upon the composition of existence and essence directs the mind beyond to the source of pure existence.

Part IV: The Absolute Simplicity of God

The composition of essence and existence identified among creatures demands an ultimate cause. Since finite essences are contingent modes of existence, there must be a necessary being of existential origin. The causal chain of potency to actuality must necessarily originate from a being of pure act, one free from all possible potency. The being of pure act must possess agency, since the causal chain of potency to actuality began rather than not. The source of all being chose whether to actualize creatures or not. This prime agent of pure act is designated by the name of God.

Now the reality of God as the prime agent of pure act must be harmonized with essence and existence. If God is pure act, then his essence must be his existence. For to be without potency is quite simply to be without any limiting essence. As it is said: “Hence God alone, who is his own act of existing, is pure and infinite act.”[11] Now what God is in and of himself is beyond comprehension, but God is known from his causal actions. As St. Thomas says: “…we cannot know what God is, only that he is…”[12] If creatures are finite compositions of essence and existence, then God is an infinite singularity of essential existence. These created essences as limited modes of existence are dependent upon God as the pure act of existence. As it is said: “Thus the act of existing is possessed by other things, from the First Agent, through a certain participation.”[13] All created compositions are not emanations of God, but they exist as contingent actualized realities from God. Thus St. Thomas refers to God as the “absolute being.”[14]The concepts of essence, existence, and act find their absolute simplicity in God.

Part V: Conclusion

The problem of the one and many is only answered in the distinction of essence and existence, the composition of creatures, and the absolute simplicity of God. In appealing to common sense, the mind experiences a multiplicity of essences that all share the unicity of existence. All these experiences must neither only be one or many, but there must be an ultimate principle of being that unites the many through the one. This metaphysical dilemma is only intensified by the subjective awareness of humanity to their own composition. To be conscious as a limited mode of existence drives the mind to find the ultimate mode of existence. The lynchpin of discovery rests on the distinction between act and potency, for essences possess a potency for existential change actualized by an external agent. There cannot be an infinite regress of potency to actuality, so there must be a primal agent of pure actuality. The essence of this prime agent must be existence, for to be pure act is be existence unbound by limitation.. This is the philosophical notion of God.

The conclusion of the absolute simplicity of God is to make the radical claim that only God is truly real. If all other things exist only as contingent realities, then creatures continuously owe their existence to participation in God. To be aware of the existential dependency upon the pure actuality of God demands a thankfulness to God. For man is held in existence only by the actuality of God, and man can potentially fall back into the void if God so permitted. God never had to actualize creation, so every moment of conscious existence is a gift from God to creation. This existential insight is the bridge between the God of philosophy and the God of religion. To ponder the absolute simplicity of God is to become aware of the compound, contingent, and finite essence of man. In doing so, man is moved by philosophy to give the ultimate honor to the absolute being, namely, God.


Clarke, W. Norris. The One and the Many. Indiana: University of Notre Dame Press, 2001.

Thomas Aquinas. An Introduction to the Metaphysics of St. Thomas Aquinas. Trans. James F. Anderson. Washington D.C.: Regnery Publishing, 2018.

Thomas Aquinas. Summa theologiae. 2nd ed. Trans.  Fathers of the English Dominican Province. At New Advent,

[1] W. Norris Clarke, The One and the Many (Indiana: University of Notre Dame Press, 2001), 34.

[2] Thomas Aquinas, An Introduction to the Metaphysics of St. Thomas Aquinas, trans. James F. Anderson (Washington D.C.: Regnery Publishing, 2018), 20.

[3] Clarke, The One and the Many, 36.

[4] Clarke, The One and the Many, 198.

[5] Thomas Aquinas, Summa theologiae, I, q. 3, a. 3, at New Advent,

[6] Thomas Aquinas, An Introduction to the Metaphysics of St. Thomas Aquinas, 23.

[7] Clarke, The One and the Many, 101.

[8] Thomas Aquinas, An Introduction to the Metaphysics of St. Thomas Aquinas, 32.

[9] Thomas Aquinas, An Introduction to the Metaphysics of St. Thomas Aquinas, 31.

[10] Thomas Aquinas, Summa theologiae, I, q. 3, a. 4, at New Advent,

[11] Thomas Aquinas, An Introduction to the Metaphysics of St. Thomas Aquinas, 32.

[12] Clarke, The One and the Many, 289.

[13] Thomas Aquinas, An Introduction to the Metaphysics of St. Thomas Aquinas, 33.

[14] Thomas Aquinas, Summa theologiae, I, q. 3, a. 7, at New Advent,

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