Informative Summary of “Ontology, or the Theory of Being” (1918)


Peter Coffey’s “Ontology, or the Theory of Being” provides a comprehensive overview of Scholastic metaphysics. It begins by defining philosophy and its distinction from special sciences and theology, emphasizing the importance of understanding ultimate causes and reasons. The text then dives into the core of ontology, meticulously analyzing the concepts of being, becoming, potentiality and actuality, and essence and existence.

The book elucidates the crucial distinction between real being and logical being, explores the nature of change and its implications for the existence of a Prime Mover, and investigates the characteristics of possible essences. Further, it tackles complex metaphysical problems like the principle of individuation and the relationship between substance and accident, offering insights into the Aristotelian categories and their modern interpretations. The text concludes with an examination of transcendental attributes of being – unity, truth, and goodness – and their relation to the beautiful, culminating in a discourse on the scope and function of fine arts.

Key Findings:

  • The text argues for the existence of a Prime Mover as a necessary consequence of the phenomenon of continuous change in the universe.
  • It posits that possible essences have their primary ideal being in the Divine Intellect and their ultimate source of possibility in the Divine Essence.
  • The book advocates for a real distinction between essence and existence in created beings, asserting that the actually existing essence is a reality distinct from the existence whereby it exists.
  • It delves into the principle of individuation, particularly in material substances, attributing it to “materia signata” – matter as allied to quantitative dimensions.
  • The text defends the reality of accidents, arguing against phenomenalist views that reduce them to mere mental constructs or aspects of substance.


  • Nature of Being: The reader learns about the various aspects of being, including its relation to actuality, possibility, essence, and existence. The concept of being is explored as a transcendental notion, wider than any genus, and its analogical predication in different contexts.
  • Becoming and Change: The text elucidates the concept of change as a transition from potentiality to actuality, involving a persistent subject and transient forms. It explores different types of change – local, quantitative, qualitative, and substantial – and their implications for our understanding of reality.
  • Essence and Existence: The reader learns about the distinction between essence (what a thing is) and existence (that it is). The text examines arguments for both real and virtual distinctions between these two concepts, particularly in contingent beings, while affirming their real identity in the Necessary Being.
  • Individuation: The principle of individuation, especially in material substances, is explained in detail. The text posits that “materia signata,” matter as allied to quantitative dimensions, individuates material substances, making them distinct and incommunicable.
  • Substance and Accident: The reader learns about the fundamental distinction between substance, a being existing in itself, and accident, a being inhering in a subject. The text analyzes the nature of accidents, their different categories, and their relationship to substance, defending the real distinction between them while emphasizing the unity of the concrete individual being.
  • Nature and Person: The concept of nature as an active principle, driving a being towards its end, is explored. The text examines the distinction between substance and nature, highlighting different perspectives on their relationship. It further delves into the concept of personality, defining it as the subsistence of a complete individual rational nature and exploring its theological implications.
  • Transcendental Attributes: The reader learns about the transcendental attributes of being – unity, truth, and goodness – and their universal applicability. The text analyzes the concept of unity and its different types, explores the nature of truth as a relation of conformity to intellect, and examines goodness as the realization of a being’s end. It further investigates the relationship between these attributes and the beautiful, culminating in a discourse on art and its function.

Historical Context:

The text was written in 1918, amidst a period of significant scientific and philosophical upheaval. The rise of modern science, particularly the success of atomism and mechanical explanations of the universe, had led to a widespread questioning of traditional metaphysical concepts like substance, accident, and causality. The text addresses these challenges, defending the validity and relevance of Scholastic metaphysics in the face of modern scientific and philosophical developments. It acknowledges the influence of modern thinkers like Descartes, Locke, Berkeley, Hume, Kant, and Spencer, while critically engaging with their ideas and offering alternative interpretations based on Aristotelian and Thomistic principles.


  1. Being is the simplest and most indeterminate of all notions. This is because it cannot be analyzed into simpler concepts and embraces all possible modes of existence.
  2. Being is predicated analogically of its various modes. This means that while the concept of being is partially the same across different modes, it also embodies differences depending on the specific mode under consideration.
  3. Logical entities have objective being only in the intellect. These are products of thought, such as abstractions and relations, and exist solely by being thought of.
  4. Actual things exist independently of their being known. Their reality doesn’t depend on perception or thought, as asserted against subjective and objective idealism.
  5. Infinite Being is the primary analogue for finite beings. This means that the concept of being is primarily and most perfectly realized in the Infinite Being, and applied to finite beings in a subordinate and dependent manner.
  6. Change is a transition of a being from one state to another. It involves a real process of becoming, not merely a substitution of things or states.
  7. Potential being requires actual being for its actualization. This forms the basis for the principle of change, stating that whatever undergoes change must be changed by something else already actual.
  8. The actual precedes the possible in the order of our knowledge. This is because our first knowledge is of actually existing things, from which we derive the concept of possibility.
  9. Substantial change involves the disappearance of one substantial form and the appearance of another. This is based on the view that every material entity is essentially composite, subject to changes in its underlying substance.
  10. The existence of a thing is the actuality of its essence. Existence is that which makes the essence actual, transferring it from the realm of possibility to actuality.
  11. God exists essentially, eternally, by His own Essence. This means that in God, essence and existence are really identical, unlike in created beings where they are distinct.
  12. The essence of a contingent being does not necessarily imply its actual existence. This is because contingent beings are dependent on God for their existence, unlike God whose essence is His existence.
  13. Possible essences as such are nothing actual, but are not unreal. They are capable of actual existence and therefore distinct from nothingness or logical entities.
  14. The Divine Essence is the ultimate source of the intrinsic possibility of all essences. This is because possible essences are intelligible as possible adumbrations or imitations of the Divine Nature.
  15. Transcendental unity is the undividedness of being. It is an attribute of all being, distinct from quantitative or mathematical unity which belongs only to quantified being.
  16. The individual alone is formally real, while the universal is fundamentally real. This is a core principle of moderate realism, asserting that while only individuals exist, universals are grounded in the real similarities between individuals.
  17. The principle of individuation in material substances is “materia signata,” matter as allied to quantitative dimensions. This explains the numerical distinction and incommunicability of material individuals.
  18. Ontological truth is the essential conformity of reality with intellect, primarily the Divine Intellect. This means that things are true because they are ultimately in accord with the Divine Mind, which is the source of their intelligibility.
  19. Ontological goodness is identical with actual being. This means that every being, in so far as it is actual, possesses some goodness or is the object of natural tendency or desire.
  20. Evil is a privation of the goodness due to a thing. It is the absence of a perfection that should be present, not a positive entity in itself.

Statistics: The text doesn’t focus on statistical data, being a philosophical treatise exploring concepts and principles rather than quantitative findings.


  1. Ontology: The philosophical study of being, its nature, and essential properties.
  2. Becoming: The process of change, transition from potentiality to actuality.
  3. Essence: What a thing is, its fundamental nature or definition.
  4. Existence: That a thing is, its actuality or presence in the real order.
  5. Potentiality: The capacity or possibility of being or becoming something.
  6. Actuality: The realization of a potentiality, the state of being something.
  7. Substance: A being existing in itself, independent of any subject.
  8. Accident: A being that inheres in a subject, dependent on substance for its existence.
  9. Nature: The essence or substance of a being, considered as the principle of its activities.
  10. Person: A subsisting being endowed with a rational nature.


  1. Golden Tower: Used to illustrate the concept of intrinsic possibility (the golden tower is possible even if it doesn’t actually exist).
  2. Square Circle: Used to illustrate the concept of intrinsic impossibility (a square circle involves a contradiction and is therefore impossible).
  3. Oak Tree: Used to explain the concepts of potentiality and actuality, as the oak is potentially present in the acorn and becomes actual through natural processes.
  4. Statue: Used to illustrate the difference between intrinsic and extrinsic possibility, as the statue is intrinsically possible in the block of marble but extrinsically possible only for a skilled sculptor.
  5. “Healthy”: Used to explain analogy of attribution, as health is properly attributed to a person but can be applied to other things in relation to that person’s health.
  6. “Seeing” with the Mind: Used to illustrate analogy of proportion, as understanding is to the mind what seeing is to the eye.
  7. “Smiling” Valley: Used to illustrate analogy of proportion, as the pleasing appearance of the valley is analogous to a smile on a human countenance.
  8. Socrates: Used to illustrate the distinction between individual and universal, as Socrates is a concrete individual embodying the universal essence of “man.”
  9. Cancer in the Stomach: Used to explain the concept of evil as a privation of good, as the cancer is a defect in the stomach’s natural function.
  10. Lying: Used to illustrate moral evil as a privation of goodness, as lying is a failure of adaptation of the moral subject to his true end.


“Ontology, or the Theory of Being” offers a rigorous and insightful exploration of Scholastic metaphysics. By meticulously analyzing key concepts like being, becoming, essence, existence, and their various relationships, it provides a framework for understanding the nature of reality and its ultimate principles. The text defends the relevance and validity of traditional metaphysics in the face of modern scientific and philosophical challenges, advocating for the importance of considering both static and dynamic aspects of reality. By examining the categories of substance and accident, exploring the intricacies of individuation, and analyzing the transcendental attributes of being, the book provides a comprehensive overview of ontology and its implications for our understanding of the world and ourselves.

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