Aquinas: On Being and Essence - Prologue. Chapter I

ON BEING AND ESSENCE

Latin: De Ente et Essentia


PROLOGUE

A slight initial error eventually grows to vast proportions, according to the Philosopher.†1 Now the first conceptions of the intellect are (as Avicenna says)†2'a being' and 'an essence'. If, then, we are to avoid mistakes through ignorance of these, we must begin exploring their difficulty by stating what is meant by saying 'a being' and 'an essence', how they are found in different things, and how they are related to the logical notions †3 of genus, species, and difference.

Chapter One

THE GENERAL MEANING OF THE TERMS 'A BEING' AND 'AN ESSENCE'

[1] We ought to get our knowledge of simple things from composite things and arrive at what is prior by way of what is posterior, so that the learning process will begin, appropriately, with what is easier. For this reason we must begin with the meaning of 'a being' and proceed to the meaning of 'an essence'.†1

[2] We must realize (with the Philosopher)†2 that the term 'a being' in itself has two meanings. Taken one way it is divided by the ten categories; taken in the other way it signifies the truth of propositions. The difference between the two is that in the second sense anything can be called a being if an affirmative proposition can be formed about it, even though it is nothing positive in reality. In this way privations and negations are called beings, for we say that affirmation is opposed to negation, and that blindness is in the eye. But in the first way nothing can be called a being unless it is something positive in reality. In the first sense, then, blindness and the like are not beings.†3

[3] The term 'an essence' is not derived from this second meaning of 'a being', for in this sense some things are called beings that do not have an essence, as is clear in the case of privations. Rather, 'an essence' is derived from 'a being' in the first meaning of the term. As the Commentator says,†4 a being in the first sense of the term is that which signifies the essence of a thing. And because, as we have said,†5'a being' in this sense is divided by the ten categories, essence must mean something common to all the natures through which different beings are placed in different genera and species, as for example humanity is the essence of man, and so with regard to other things.

[4] Because the definition telling what a thing is signifies that by which a thing is located in its genus or species, philosophers have substituted the term 'quiddity' for the term 'essence'. The Philosopher frequently calls this 'what something was to be';†6 that is to say, that which makes a thing to be what it is. It is also called 'form',†7 because form signifies the determination †8 of each thing, as Avicenna says.†9 Another term used for this is 'nature', using 'nature' in the first of the four senses enumerated by Boethius.†10 In this sense anything is called a nature which the intellect can grasp in any way; for a thing is intelligible only through its definition and essence. That is why the Philosopher, too, says that every substance is a nature.†11 The term 'nature'†12 in this sense seems to mean the essence of a thing as directed to its specific operation, for no reality lacks its specific operation. The term 'quiddity' is derived from what is signified by the definition, while 'essence'†13 is used because through it, and in it, that which is has being.†14

[5] Because we use the term 'a being' absolutely and primarily of substances,†15 and secondarily and with qualification of accidents, it follows that essence is in substances truly and properly, but in accidents in a restricted way and in a qualified sense.

[6] Furthermore, some substances are simple and some composite,†16 and essence is in both; but it is present in simple substances more truly and perfectly because they also have being more perfectly. Simple substances are also the cause of those that are composite; at least this is true of the primary and simple substance, which is God. But because the essences of these substances are to a greater degree hidden from us, we must start with the essences of composite substances, so that the learning process will begin, appropriately, with what is easier.

Reproduced from:

ST. THOMAS AQUINAS


ON BEING AND ESSENCE


Translated with an Introduction and Notes

by

ARMAND MAURER, C.S.B.


SECOND REVISED EDITION


THE PONTIFICAL INSTITUTE OF MEDIAEVAL STUDIES


On Being and Essence Bibliographic Data p 4
LIBRARY OF CONGRESS CATALOGING DATA (Revised)
Thomas Aquinas, Saint, 1225?-1274.
On being and essence. Tr., with an introd. and notes, by Armand Maurer. 2d. rev. ed. Toronto, Pontifical Institute of Mediaeval Studies, 1968.
(Mediaeval sources in translation; I ISSN 0316-0874)
79 p.
Bibliography: p. [73]-76.
Index: p. [77]-79.
ISBN 0-88844-250-5
B765.T53D431968189':4

First edition 1949
Second edition 1968
Reprinted 1991
(c) 1949, 1968, 1991 by

Pontifical Institute of Mediaeval Studies
59 Queen's Park Crescent East
Toronto, Ontario, Canada MSS 2C4
Reprinted by Universa, Wetteren, Belgium