The Use of the Categories in
Grammar and Definition

Throughout Part One the categories are used both to explain grammatical relations and as a help to the correct definition of technical terms. The following materials may be of assistance in the study of the categories.


In using the following tables the student should recall that, strictly speaking, only natural, real entities can be properly classified in the categories. Mental relations and artificial numbers, for example, are included in these tables only reductively, as bearing a resemblance to the natural and real entities with which they are grouped, since art imitates nature. These tables are based on the writings of St. Thomas Aquinas and his noted follower John of St. Thomas. The table of artificial things was suggested by the classification given by Hugh of St. Victor and St. Bonaventure.




    1. Poetic description:

The moon above the eastern wood
Shone at its full; the hill-range stood
Transfigured in the silver sheen,
Its blown snows flashing cold and keen,
Dead white, save where some sharp ravine
Took shadow, or the sombre green
Of hemlocks turned to pitchy black
Against the whiteness at their back.
For such a world and such a night
Most fitting that unwarming light,
Which only seemed where'er it fell
To make the coldness visible.
    -John Greenleaf Whittier, "Snowbound." The whole poem is descriptive in character.

       b. The following is Pope's description of the Sylphs, or fairies,
whom he pictures fluttering about Belinda, the heroine of "The Rape of the
Lock," as she goes boating on the Thames.

Some to the sun their insect-wings unfold,
Waft on the breeze, or sink in clouds of gold;
Transparent forms, too fine for mortal sight,
Their fluid bodies half dissolved in light,
Loose to the wind their airy garments flew,
Thin glitt'ring textures of the filmy dew,
Dipped in the richest tinctures of the skies,
Where light disports in ever-mingling dyes,
While ev'ry beam new transient colors flings,
Colors that change whene'er they wave their wings.

2. Rhetorical description:
      a. The following is taken from a speech for the prosecution given by Daniel Webster in a well-known murder trial:
An aged man, without an enemy in the world, in his own house and in his own bed, is made the victim of a butcherly murder, for mere pay. Truly, here is a new lesson for painters and poets. Whoever shall hereafter draw the portrait of murder, if be will show it as it has been exhibited in an example, where such example was last to have been looked for, in the very bosom of our New England society, let him not give it the grim visage of Moloch, the brow knitted by revenge, the face black with settled hate, and the bloodshot eye emitting livid fires of malice. Let him draw, rather, a decorous, smoothfaced, bloodless demon; a picture in repose, rather than in action; not so much an example of human nature in its depravity and in its paroxysms of crime, as an infernal nature, a fiend, in the ordinary display and development of his character.

The deed was executed with a degree of self-possession and steadiness equal to the wickedness with which it was planned. The circumstances, now clearly in evidence, spread out the whole scene before us. Deep sleep has fallen on the destined victim and all beneath his roof. A healthful old man, to whom sleep was sweet, the first sound slumbers of the night held in their soft but strong embrace. The assassin enters, through the window already prepared, into an unoccupied apartment. With noiseless feet he paces the lonely hall, a hall lighted by the moon; he winds up the ascent of stairs and reaches the door of the chamber. Of this, he moves the lock, by soft and continued pressure, till it turns on its hinges without noise; and he enters and beholds his victim before him. The room was uncommonly open to the admission of light. The face of the innocent sleeper was turned from the murderer, and the beams of the moon, resting on the gray locks of his aged temple, showed him where to strike. The fatal blow is given; and the victim passes, without a struggle or a motion, from the repose of sleep to the repose of death! It is the assassin's purpose to make sure work; and he yet plies the dagger, though it was obvious that life bad been destroyed by the blow of the bludgeon. He even raises the aged arm, that he may not fail in his aim at the heart, and replaces it over the wounds of the poniard! To finish the picture, he explores the wrist for the pulse! He feels for it and ascertains that it beats no longer! It is accomplished. The deed is done. He retreats, retraces his steps to the window, passes out through it as he came in and escapes. He has done the murder -- no eye has seen him, no ear has heard him. The secret is his own, and it is safe!
    -- Daniel Webster, "Exordium in the Knapp Murder Case."


    1. Scientific description:* [* From Birds of America, edited by T. Gilbert Pearson, with permission of Doubleday and Company, Incorporated, New York City.]

MOCKINGBIRD: Mimus polyglottos (Linnaeus).

Other names: Mock Bird; Mocking Thrush; Mimic Thrush; Mocker.

General Description. -- Length, 10 inches. Upper parts, brownish-gray; under parts, white and gray. Bill, shorter than head; wings, long and rounded; tail, longer than wing, rounded, the feathers moderately broad with rounded tips.

Color. -- Above, plain brownish gray; wings and tail, dull blackish-slate with pale slate-gray edgings, these broadest on secondaries (especially the terminal portion, where sometimes inclining to white); middle and greater wing-coverts, narrowly tipped with dull white or grayish-white, forming two narrow bands (these indistinct in worn plumage); primary coverts, white usually with a subterminal spot or streak of dusky; base of primaries, white, this most extended on the two innermost, where occupying at least basal half of both webs, often much more, that on the longer quills sometimes entirely concealed by overlying primary coverts; outermost tail-feather, white, sometimes with a trace of dusky or grayish on outer web; second, with outer web mostly blackish, the inner web mostly white; third, blackish or dusky, was about half of the terminal and basal portions white; a very indistinct stripe over eye of pale grey; eyelids, grayish-white; lores, dusky; sides of bead, grayish, indistinctly streaked with whitish; space below the eyes and checks, dull white, usually faintly barred or transversely flecked with grayish or dusky; chin and throat, dull white, margined along each side by a dusky streak; chest and sides of breast, pale smoke-gray, passing into a more buffy hue on sides and flanks; the under tail-coverts, pale buff; abdomen and center of breast, white; bill, black.

Nest and Eggs. -- Nest: Composed of twigs, grasses and weeds, lined with fine rootlets, moss, and sometimes cotton; placed in many different locations but usually in a deep bramble thicket or hedge; as a rule they are located within ten feet of the ground, never on it, and have been seen built fifty feet above the earth. Eggs: 4 to 6, bluish-green heavily freckled with several shades of brown.

Distribution. -- Eastern United States; northward regularly (but locally), to Maryland, southern Ohio, southern half of Indiana and Illinois, Missouri, etc., irregularly to Massachusetts, southeastern New York (Long Island, etc.), New Jersey, Pennsylvania, northern Indiana and Illinois, and Iowa, sporadically to Maine, Ontario, southern Wisconsin (breeding), and southern Minnesota; breeding and resident throughout its range, except where occurring accidentally; southward to southern Florida and along the Gulf to eastern Texas, and to the Bahamas; introduced into Bermuda (1893).

Habits. -- The Mockingbird stands unrivaled. He is the king of song. This is a trite saying, but how much it really means can be known only to those who have heard this most gifted singer uncaged and at his best in the lowlands of the Southern States. He equals and even excels the whole feathered choir. He improves upon most of the notes he reproduces, adding also to his varied repertoire the crowing of chanticleer, the cackling of the hen, the barking of the house dog, the squeaking of the unoiled wheel barrow, the postman's whistle, the plaints of young chickens and turkeys and those of young wild birds, not neglecting to mimic those of his own offspring. He even imitates man's musical inventions. Elizabeth and John Grinnell assert that a Mockingbird was attracted to a phonograph on the lawn where, apparently he listened and took mental notes of the performance, giving the next day, a week later, or at midnight an entertainment of his own and then repeating it with the exact phonograph ring. Even the notes of the piano have been reproduced in some cases and the bird's vocalization simulates the lightning changes of the kaleidoscope.

The Mocker is more or less a buffoon, but those who look upon him only as an imitator or clown have much to learn of his wonderful originality. His own song is heard at its best at the height of the love season, when the singer flutters into the air from some tall tree-top and improvises his music, pouring out all the power and energy of his being in such an ecstacy of song that, exhausting his strength in the supreme effort, he slowly floats on quivering, beating pinions down through the bloom-covered branches until, his fervor spent, he sinks to the ground below. His expanded wings and tail flashing white in the sunlight and the buoyancy of his action appeal to the eye as his music captivates the ear. On moonlit nights at this season the inspired singer launches himself far into the air, filling the silvery spaces of the night with the exquisite swells and trills, liquid and sweet, of his unparalleled melody. The son, rises and falls as the powers of the singer wax and wane, and so he serenades his mate throughout the livelong night. One such singer wins others to emulation and, as the chorus grows, little birds of the field and orchard wake just enough to join briefly in the swelling tide of avian melody.

The Mockingbird seldom holds himself aloof from mankind, but often makes himself at home in the dooryard, sits on the chimney top and, like the Robin in the North, "knows all the folks." The negroes close the shutters of their cabins at night, but they say that the Mocker sings down the chimney." Often the nest is placed in shrub or hedge close by the house; as soon as the young are hatched the parents take pains to proclaim their whereabouts that all may, know. Therefore, the young, which are in demand as cage birds, frequently are taken and sold into captivity.

The Mockingbird has many traits that endear it to all. It is brave and devoted, attacking birds twice its size, dogs, cats, and even man himself in defense of his young. Its cries of alarm give warning to all other birds nearby. When kindly treated it may even come in at the door or window. Thus it has won for itself a high place in the regard and affection of the Southern people.
    -- Edward Howe Forbush in Birds of America, edited by T. G. Pearson.

2. Some technical definitions:

    a. Grammar:

The following are definitions of a verb given by a number of different grammars. Which is best?

(1) A verb is a word which signifies to be, to do, or to be acted upon.
(2) A verb is a word which expresses action or helps to make a statement.
(3) A verb is a word used to express action or state of being.
(4) A verb is a word which asserts something.
(5) A verb is a word denoting actions, states, or happenings,
(6) A verb is a word which, expressing an act, occurrence, or mode of being, carries the distinctive force of a predicate.
(7) A verb is a word which affirms or predicates something.
(8) A verb is a word which predicates something of a subject.
(9) A verb is a word which by human agreement expresses an attribute of a subject along with time.
See also the definitions given at the end of each chapter in this book.

    b. Geometry:

(1) A circle is a line all points of which are equidistant from a fixed point called the center.
(2) A triangle is a three-sided closed plane figure.
(3) A parallelogram is a closed plane figure whose sides are straight lines and whose opposite sides are parallel.
(4) A rectangle is a parallelogram with one right angle.

    c. Algebra:

(1) An equation is an algebraic statement that two quantities are equal.
(2) A proportion is a statement that two ratios are equal.
(3) If one quantity depends upon another quantity for its value, it is said to be a function of that quantity.
(4) A number is a quantity whose parts have no common boundary.

    d. Biology:

In the maintenance of its life, every living thing exhibits a phenomenon which consists essentially in the breaking down of complex substances into simpler ones, with consequent release of energy. This phenomenon has been called "dissimilation" in contrast to "assimilation" in which simple substances are absorbed and built up into the organism in the form of substances of greater complexity and higher energy content. Although this dissimilation affects different materials in different species, it very commonly involves the breaking down, by oxidation, of carbohydrates and fats, the end-products being carbon dioxide and water. The dissimilation process thus involves an exchange of gases between the organism and its environment, oxygen being absorbed and carbon dioxide evolved. This exchange of gases, so characteristic in animals, is equally characteristic of the vast majority of plants. Hence the term "respiration," used to denote this gaseous exchange and the processes of which it forms a part, is equally applicable to animals and plants.

Although the term respiration at first referred to the exchange of gases between the organism and its environment, so that, in the case of animals, it was synonymous with the term breathing, it has for many years now been more usual to regard respiration as involving the whole of the dissimilation process. The leading workers of the second half of the nineteenth century, such as Sachs, Pfeffer and Palladin, who were responsible for the modern conception of respiration, all gave the word respiration this wider meaning, and in this book respiration in plants is taken to include all the phenomena of dissimilation, the characteristics of which are the breaking down of complex substances into simpler ones with a consequent release of energy.
    -- W. Stiles and W. Leach, Respiration in Plants *
[* Reprinted by permission of Methuen and Company, Limited.]

    e. Physical Science:

(1) To be strictly accurate, an element is a substance, all of whose atoms contain the same number of protons. However, until you study more about the structure of atoms it will be useful and accurate to think of an element as a simple substance which cannot be broken up into any simpler substances by ordinary chemical means. When a chemist attempts the analysis of an element such as iron, be finds that it is made up entirely of iron. He has reached the limits of chemical analysis.
-- G. M. Raulins and A. H. Struble, Chemistry in Action (1940)**
[** By permission of the author and D. C. Heath and Company, Boston.]

(2) What causes lightning? Scientists do not know certainly what causes lightning. The following theory is as good as any,

When a liquid is broken up into a spray, friction charges the larger droplets positively and the smaller ones negatively. In a thundercloud there are huge upward winds with velocities as great as 200 miles per hour. These winds break up raindrops and carry the smaller, negatively charged drops to the top of the cloud, while the larger, positively charged ones remain behind. Often the charges jump from one part of the cloud to another in a lightning stroke. Sometimes a wind carries away the minus-charged top of the cloud. Then the positively charged remainder is likely to be discharged to the earth.

What causes thunder? A lightning stroke heats the air through which it passes, and the air expands suddenly, causing thunder.
-- O. H. Blackwood, W. B. Herron, and W. C. Kelly, High School Physics (1951)* [* This and the following quotation are reprinted by permission of the authors and Ginn and Company, Boston.]

(3) What is work?

You have learned that a force is a push or pull and that you must exert a force to lift a market basket. You have found also that a force is required to overcome friction when you move an object. Now you will see how a force can do work in lifting a body or in overcoming a friction.

The word work is one of the oldest in the English language. It often means effort, perhaps unpleasant, for which you get paid. Thus we say that a golf caddy "works" when he stands idly by, watching a player hit a ball. A watchman "works" as he sits at a railroad crossing. You "work" a problem in algebra. In physics we try to give only one meaning to every word; it is important that you know just what physicists mean by work.

When you carry a suitcase upstairs, you do work: for you exert an upward force on the suitcase, and you lift it upward. A horse does work in pulling a plow over a field, for lie exerts a forward force which moves the plow forward. To do work on a body, you must exert a force on it and must move it in the direction of the force.

We define work as the product of the force exerted on a body times the distance that the body moves in the direction of the force.

 Work = force × distance moved
    W = f × d 

    f. Christian Doctrine:

(1) A sacrament is an outward sign instituted by Christ to give grace.
(2) Baptism is the sacrament that gives our souls the new life of sanctifying grace by which we become children of God and heirs of heaven. The priest is the usual minister of baptism but if there is danger that someone will die without baptism, anyone may and should baptize. It is given by pouring ordinary water on the forehead of the person to be baptized, saving while pouring it: "I baptize thee in the name of the Father, and of the Son, and of the Holy Ghost."
(3) The Church is the congregation of all baptized persons united in the same true faith, the same sacrifice, and the same sacraments, under the authority of the Sovereign Pontiff and the bishops in communion with him, founded by Jesus Christ to bring all men to eternal salvation.
(4) A mortal sin is a grievous offense against the law of God, which deprives the sinner of sanctifying grace, consisting in a thought, desire, word, action, or omission which is seriously wrong, of whose evil the sinner is mindful at the time of acting, and to which he fully consents.


A. How logical relations are expressed by grammatical relations.

 1. Substance is expressed by a noun.
    Its differences are often expressed by adjectives.
 2. Accidents when thought of as if they were substances are
    expressed in the same way as substance.
 3. Accidents when predicated as properties or contingents
    (modifiers) are expressed as follows:
    a. Quantity is expressed by a noun, adjective, or by a plural form.
       Frequently it is indicated by a relation of greater or smaller.
    b. Quality is expressed by an adjective.
       Occasionally it is indicated by a relation.
    c. Relation is expressed by a preposition.
       Sometimes it is indicated by a noun connoting a relation.
    d. Action, passion, position, vestition are expressed by verbs or verbals.
    e. Place and position are expressed as if they were relations, by prepositions.
       They are also expressed by adverbs.
    f. Timing is expressed by the tense of the verb.
       It is also indicated by, adverbs and, as if they were relations, by prepositions.
 4. The relation of predication is expressed by the copula,
    and implicitly by all words used as modifiers.
 5. The relations of argument are expressed by a (pure) conjunction.

B. How grammatical relations indicate logical relations: 1. Nouns primarily indicate substances; secondarily they indicate parts of substances and accidents considered as substances. Infinitives are nouns which name an action or reception, but sometimes have adjectival or adverbial uses. 2. Pronouns substitute for nouns, and sometimes indicate gender, number, and case for purpose of identifying the noun to which they refer. 3. Adjectives primarily express quality, but may express other accidents considered as modifications of substance. The article is a particular kind of adjective used before nouns to limit their extension. The participle is an adjective which expresses action or reception. It is determined by objects just like a verb, and may also be used in place of infinitive as a noun (gerund). 4. Verbs: The copulative verb expresses the act of judgment. Other verbs express action or reception along with timing (tense) and show agreement in number and gender with their subject. Secondarily they may express the manner and other circumstances of the action through mood and by auxiliaries. 5. Adverbs primarily express a mode or manner of an action. Secondarily they express timing or location, or the modes of other accidents. 6. Prepositions primarily express relation. Secondarily they express location, position, timing, and other categories considered as relations. 7. Conjunctions, when pure, express relations between premises of an argument. Adverbial conjunctives also have the functions of adverbs. 8. Interjections express a sudden or strong emotion. Sometimes they imply an imperative statement.


A. Outline of the Lord's Prayer

St. Thomas Aquinas, O.P., in his commentaries gives excellent examples of how to outline a work in preparation to explaining it. The following explanation of the Lord's Prayer shows how his method proceeds:

The Lord's Prayer is most perfect, because, as Augustine says, "If we pray rightly and fittingly, we can say nothing else but what is contained in this prayer of our Lord." For since prayer interprets our desires, as it were, before God, then alone is it right to ask for something in our prayers when it is right that we should desire it. Now in the Lord's Prayer not only do we ask for all that we may rightly desire, but also in the order wherein we ought to desire them, so that this prayer not only teaches us to ask, but also directs all our affections.

Thus it is evident that the first thing to be the object of our desire is the end, and afterwards whatever is directed to the end. Now our end is God towards whom our affections tend in two ways: first, by our willing the glory of God, secondly, by willing to enjoy his glory. The first belongs to the love whereby we love God in himself, while the second belongs to the love whereby we love ourselves in God. Wherefore the first petition is expressed thus: Hallowed be thy Name, and the second thus: Thy kingdom come, by which we ask to come to the glory of the kingdom.

To this same end a thing directs us in two ways: in one way, by its very nature; in another way, accidentally. Of its very nature the good which is useful for an end directs us to that end. Now a thing is useful in two ways to that end which is beatitude: in one way, directly and principally, according to the merit whereby we merit beatitude by obeying God, and in this respect we ask: Thy will be done on earth as it is in heaven; in another way instrumentally, and, as it were, helping us to merit, and in this respect we say: Give us this day our daily bread, whether we understand this of the sacramental Bread, the daily use of which is profitable to man, and in which all the other sacraments are contained, or of the bread of the body, so that it denotes all sufficiency of good, as Augustine says, since the Eucharist is the chief sacrament, and bread is the chief food: thus in the gospel of Matthew we read, supersubstantial, i.e., principal, as Jerome expounds it.

We are directed to beatitude accidentally by the removal of obstacles. Now there are three obstacles to our attainment of beatitude. First, there is sin, which directly excludes a man from the kingdom, according to I Cor. 6:9-10: "Neither fornicators, nor idolaters, etc., shall possess the kingdom of God"; and to this refer the words, Forgive us our trespasses. Secondly, there is temptation, which hinders us from keeping God's will, and to this we refer when we say: And lead us not into temptation, whereby we do not ask not to be tempted, but not to be conquered by temptation, which is to be led into temptation. Thirdly, there is the present penal state which is a kind of obstacle to a sufficiency of life, and to this we refer in the words, Deliver us from evil."
    -- Summa Theologiae,II-II, q. 83, a. 9*
[*Reprinted from the Summa Theologica, Benziger Bros. Inc., publishers and copyright owners.]

B. St. Thomas' division in the ordinary outline form:

Thesis: The seven petitions of the Lord's Prayer include all the
things we rightly desire and in the right order of importance.
I. The thing which we must desire above all things is God, who is our end
   and our beatitude.
  1. We must first desire that God should be glorified in himself, and
     hence we pray: "Our Father who art in heaven, hallowed be thy name."
  2. We must desire that God should be glorified in us, that is, that
     we should enjoy his glory; and hence next we pray: "thy Kingdom come."
II. Whatever else we desire we must desire as a means useful to achieve
    our end, which is God, our beatitude.
  1. Some means are desired because they are by their very nature
     necessary to attain this end.
     a. Merit is a means which is directly and principally useful to
        attain our end, and hence next we pray: "Thy will be done on
        earth as it is in heaven."
     b. Other things are means which are instrumentally useful to attain
        our end because they assist in gaining merit, and for them we
        next pray: "Give us this day our daily bread."
  2. Other means are desired because they are accidentally necessary to
     attain this end, by removing obstacles to attaining it.
     a. They may remove obstacles directly opposed to our end, namely,
        sin, and hence next we pray: "Forgive us our trespasses as we
        forgive those who trespass against us."
     b. They may remove obstacles indirectly opposed to our end.
       (1) These obstacles are indirectly opposed to our end, because
           they hinder us from doing God's will, namely, occasions of
           sin; and hence we next pray: "Lead us not into temptation."
       (2) These obstacles are indirectly opposed to our end by limiting
           our full development -- such are the effects of sin felt in
           this life; and hence lastly we pray: "Deliver us from evil."