Essence is properly described as that whereby a thing is what it is. Existence is that whereby the essence is an actuality in the line of being
Essence and Existence (Lat. essentia, existentia).—Since they are transcendentals, it is not possible to put forward a strict definition of either of the subjects of the present article. Essence, however, is properly described as that whereby a thing is what it is, an equivalent of the to ti en einai of Aristotle (Metaph., VII, 7). The essence is thus the radical or ground from which the various properties of a thing emanate and to which they are necessarily referred. Thus the notion of the essence is seen to be the abstract counter-part of the concrete entity; the latter signifying that which is or may be (ens actu, ens potentiae), while the former points to the reason or ground why it is precisely what it is. As furnishing in this manner an answer to the question What? (Quid?)—as, e.g., What is man?—essence is equivalent to quiddity; and thus, as St. Thomas remarks (I, Q. iii, a. 3), the essence of a thing is that which is expressed by its definition. Essence and nature express the same reality envisaged in the two points of view as being or acting. As the essence is that whereby any given thing is that which it is, the ground of its characteristics and the principle of its being, so its nature is that whereby it acts as it does, the essence considered as the foundation and principle of its operation. Hence again St. Thomas: "Nature is seen to signify the essence of a thing according as it has relation to its proper operation" (De ente et essentiae, cap. i). Furthermore, essence is also in a manner synonymous with form, since it is chiefly by their formal principle that beings are segregated into one or other of the species. Thus, while created spiritual things, because they are not composed of matter and form, are specifically what they are by reason of their essences or "forms" alone, the compounded beings of the corporeal world receive their specification and determination of nature, or essence, principally from their substantial forms. A further synonym of essence is species; but it is to be carefully noted that essence in this connection is used rather with a logical or metaphysical connotation than with a real or physical one. This distinction is of considerable importance. The real or physical essence of compound entities consists in, or results from, the union of the constituent parts. Thus if we consider man as a being composed of matter and form, body and soul, the physical essence will be the body and soul. Apart from any act of abstraction, body and soul exist in the physical order as the constituents of man. On the other hand, we may consider man as the result of a composition of genus proximum and differentia ultima, i.e. of his animality and his rationality. Here the essence, humanity, is metaphysical or logical. Thus, while the real essence, to speak still only of composite beings, consists in the collection of all those physical component parts that are required to constitute the entity what it is, either actually or potentially existent, without which it can be neither actual nor potential, the logical essence is no more than the composition of ideas or notions, abstracted mentally and referred together in what are known as "second intentions".
This consideration provides a basis for the distinction of essences according to the degree of physical and metaphysical complexity or simplicity which they severally display. The Supreme Being has—or rather is—a unique and utterly simple essence, free from all composition, whether physical or metaphysical. Moreover, in God—otherwise, as we shall see, than in creatures—there is no distinction of any kind between His essence and His existence. Spiritual created beings, however, as free from the composition of matter and form, have physically simple essences; yet they are composite in that their essences are the result of a union of genus and differentia, and are not identical with their existence. In the angel the essence is the species consequent on this union. Corporeal creatures not only share in metaphysical complexity of essence, but have, on account of their material composition, a physical complexity as well.
The characteristic attributes of the essence are immutability, indivisibility, necessity, and infinity.—Since the essence of anything is that whereby the thing is what it is, it follows directly from the principle of contradiction that essences must be immutable. This, of course, is not true in the sense that physical essences cannot be brought into being or cease to exist, nor that they cannot be decomposed into their constituent parts, nor yet that they are not subject to accidental modification. The essence of God alone, as stated above, is so entirely free from any sort of composition that it is in the strictest sense immutable. Every essence, however, is immutable in this, that it cannot be changed or broken up into its constituent parts and yet remain the same essence. The attribute is transcendental and is applied to essence precisely as it is essence. Thus, while the essence of any given man may be broken up into body and soul, animality and rationality, man as man and humanity as humanity is changeless. One individual ceases to exist; the essence itself, whether verified or not in concrete actuality, persists. The definition, "man is a rational animal", is an eternally immutable truth, verifiable whenever and wherever the subject man is given, either as a concrete and existent entity, or as a mere potentiality. Similarly, essences are said to be indivisible; that is to say, an essence ceases to be what it is when it is broken up into its constituents. Neither body nor soul alone is man. Neither animality nor rationality, taken separately, is humanity. Therefore, precisely as essence, it is indivisible. In like manner necessity is predicated of essences. They are necessary in that, though they may be merely possible and contingent, each must of necessity always be itself. In the order of actual being, the real essence is necessarily what it is, since it is that whereby the thing is what it is; in the order of the merely possible, it must necessarily be identical with itself. Finally, essences are said to be eternal and infinite in the negative sense that, as essences, there is no reason for their non-existence, nor for their limitation to a given number of individuals in any species. From what has been said, the distinction between essence considered as physical and as metaphysical will be apparent. It is the metaphysical essence that is eternal, immutable, indivisible, necessary, etc.; the physical essence that is temporal, contingent, etc. In other words, the meta-physical essence is a formal universal, while the physical essence is that real particularization of the universal that provides the basis for the abstraction.
So far the present article has been occupied in exhibiting the Scholastic view with regard to essence, and in obtaining a certain precision of thought rather than in raising any problems intimately connected with the subject. Notice must be taken, however, of a philosophical tradition which has found adherents mainly among British philosophers and which is at variance with the Scholastic. This tradition would treat as futile and illusory any investigation or discussion concerning the essences of things. By those who hold it, either the fact of essence is flatly denied and what we conceive of under that name is relegated to the region of purely mental phenomena; or, what practically amounts to the same thing, that fact is judged to be doubtful and consequently irrelevant; or again, while the fact itself may be fully admitted, essence is declared to be unknowable, except in so far as we may be said to know that it is a fact. Of those who take up one or other of these positions with regard to the essence of things, the most prominent may be cited. Hobbes and Locke, Mill, Hume, Reid, and Bain, the Positivists and the Agnostics generally, together with a considerable number of scientists of the present day, would not improperly be described as either doubtful or dogmatically negative as to the reality, meaning, and cognoscibility of essence. The proponents and defenders of such a position are by no means always consistent. While they make statements of their case, based for the most part on purely subjective views of the nature of reality, that the essences of beings are nonentities, or at least unknowable, and, as a consequence, that the whole science of metaphysics is no more than a jargon of meaningless terms and exploded theories, they, on the other hand, express opinions and make implicit admissions that tell strongly against their own thesis. Indeed, it would generally seem that these philosophers, to some extent at least, misunderstand the position which they attack, that they combat a sort of intuitive knowledge of essences, erroneously supposed by them to be claimed by Scholastics, and do not at all grasp the theory of the natures of things as derived from a pains-taking consideration of their characteristic properties. Thus even Bain admits that there may in all probability be some one fundamental property to which all the others might be referred; and he even uses the words "real essence" to designate that property. Mill tells us that "to penetrate to the more hidden agreement on which these more obvious and superficial agreements (the differentiae leading to the greatest number of interesting propria) depend, is often one of the most difficult of scientific problems. And as it is among the most difficult, so it seldom fails to be among the most important". Father Rickaby in his "General Metaphysics" gives the citations from both Mill and Bain, as well as an important admission from Comte, that the natural tendency of man is to inquire for persistent types, a synonym, in this context, for essences. The philosophical tradition, or school, to which allusion is made—although we have anticipated its assertions by the admissions into which its professors have allowed themselves to be drawn by the exigencies of reason and human language—may be divided roughly into two main classes, with their representatives in Locke and Mill. Locke got rid of the old doctrine by making the "supposed essences" no more than the bare significations of their names. He does not, indeed, deny that there are real essences; on the contrary, he fully admits this. But he asserts that we are incapable of knowing more than the nominal or logical essences which we form mentally for ourselves. Mill, though, as we have seen, he occasionally abandons his standpoint for one more in keeping with the Scholastic view, professedly goes further than Locke in utterly rejecting real essences, a rejection quite in keeping with his general theory of knowledge, which eliminates substance, causality, and necessary truth.
The considerations previously advanced will serve to indicate a line of argument used against scepticism in this matter. The Scholastics do not and never have claimed any direct or perfect acquaintance with the intimate essences of all things. They recognize that, in very many cases, no more than an approximate knowledge can be obtained, and this only through accidental characteristics and consequently by a very indirect method. Still, though the existence of the concrete beings, of which the essences are in question, is contingent and mutable, human knowledge, especially in the field of mathematics, reaches out to the absolute and necessary. For example, the properties of a circle or triangle are deducible from its essence. That the one differs specifically from the other, and each from other figures, that their diverse and necessary attributes, their characteristic properties, are dependent upon their several natures and can be inferred by a mathematical process from these—so much we know. The deductive character of certain geometrical proofs, proceeding from essential definitions, may at least be urged as an indication that the human mind is capable of grasping and of dealing with essences.
Similarly, and even from the admissions of the opponents of the Scholastic tradition given above, it may reasonably be maintained that we have a direct knowledge of essence, and also an indirect, or inductive knowledge of the physical natures existent in the world about us. The essences thus known do not necessarily point to the fact of existence; they may or may not exist; but they certify to us what the things in question are. The knowledge and reality of essences emerges also from the doctrine of universals, which, although formally subjective in character, are true expressions of the objective realities from which they are abstracted. As Father Rickaby remarks: "In the rough the form of expression could hardly be rejected, that science seeks to arrive at the very nature of things and has some measure of success in the enterprise"; and again, "In short, the very admission that there is such a thing as physical science, and that science is cognitio rerum per causas—a knowledge of things, according to the rationale of them—is tantamount to saying that some manner of acquaintance with essences is possible; that the world does present its objects ranged according to at least a certain number of different kinds, and that we can do something to mark off one kind from another." (General Metaphysics, c. III.)
Existence is that whereby the essence is an actuality in the line of being. By its actuation the essence is removed from the merely possible, is placed outside its causes, and exists in the world of actual things. St. Thomas describes it as the first or primary act of the essence as contrasted with its secondary act or operation (I Sent., dist. xxxiii, Q. i, a. 1, ad 1); and again, as "the actuality of all form or nature" (Summa, I, Q. iii, a. 4). Whereas the essence or quiddity gives an answer to the question as to what the thing is, the existence is the affirmative to the question as to whether it is. Thus, while created essences are divided into both possible and actual, existence is always actual and opposed by its nature to simple potentiality. With regard to the existence of things, the question has been raised as to whether, in the ideal order, the possible is antecedent to the actual. The consideration here does not touch on the real or physical order, in which it is conceded by Scholastics that the potentiality of creatures precedes their actuality. The unique actuality, pure and simple (as against such theorists as von Hartmann, maintaining an absolute primitive potentiality of all existence), that necessarily precedes all potentiality, is that of God, in Whom essence and existence are identical. We are concerned with the question: Is the concept of a possible entity prior to that of an existing one? Rosmini answers this question in the affirmative. The School generally takes the opposite view, maintaining the thesis that the primitive idea is of existent entity—that is, essence as actualized and placed outside of its causes—in the concrete, though confused and indeterminate. Such an idea is of narrow intension, but extensively it embraces all being. The thesis is supported by various considerations, such as that the essence is related to its existence as potential to actual, that the act generally is prior to potentiality, and that this latter is known, and only known, through its corresponding actuality. Or, we know the possible being as that which may be, or may exist; and this necessary relation to actual existence, without which the possible is not presented to the mind, indicates the priority, in the line of thought, of the actually existent over the merely possible. Existence is thus seen to be in some sense distinguished from the essence which it actuates.
The question agitated in the School arises at this point: What is the nature of the distinction that obtains between the physical essence and the existence of creatures? It is to be borne in mind that the controversy turns not upon a distinction between the merely possible essence and the same essence as actualized, and thus physically existent; but on the far different and extremely nice point as to the nature of the distinction to be drawn between the actualized and physically existent essence and its existence or actuality, by which it is existent in the physical order. That there is no such distinction in God is conceded by all. With regard to creatures, several opinions have been advanced. Many Thomists hold that a real distinction obtains here and that the essence and existence of creatures differ as different entities. Others, among them Dominicus Soto, Lepidi, etc., seem to prefer a distinction other than real. The Scotists, affirming their "formal distinction", which is neither precisely logical nor real, but practically equivalent to virtual, decide the point against a real distinction. Suarez, with many of his school, teaches that the distinction to be made is a logical one. The principal arguments in favor of the two chief views may be summarized as follows:
Thornists: (a) If essence and existence were but one thing, we should be unable to conceive the one without conceiving the other. But we are as a fact able to conceive of essence by itself. (b) If there be no real distinction between the two, then the essence is identical with the existence. But in God alone are these identical.
Suarez: (a) A real physical essence is actual in the line of being and not merely possible. But this actuality must belong to it, as a physical essence; for it is, ex hypothesi, neither nothing nor merely possible, and the actuality of an essence is its existence. Cardinal Franzelin cast the argument in this form: "Est omnino evidens in re positae, extra suas causas, in statu actualitatis, ne ratione quidem abstrahi posse formalem existentiam" (De Verbo Incarnato). (b) It is inconceivable how the existence of a real or physical essence should differ from the essence of its existence.
These positions are maintained, not only by argument, but by reference to the authority and teaching of St. Thomas, as to whose genuine doctrine there is considerable difference of opinion and interpretation. It does not, however, appear to be a matter of great moment, as Soto remarks, whether one holds or rejects the doctrine of a real distinction between essence and existence, so long as the difference between God and His creatures is safe-guarded, in that existence is admitted to be of the essence of God and not of the essence of creatures. And this would seem to be sufficiently provided for even in the supposition that created essences are not distinct from their existences as one thing is from another, but as a thing from its mode.