The period extending from the Council of Nicaea (325) to the end of the
fifth century was one of great literary and speculative activity in the
Christian Church; for, although the definitions of the council stayed
the progress of the Arian heresy, still the contest with the Arians was
by no means ended. Day by day the theology of the Church was organized
into a system which offered an impregnable front to heretic and
schismatic, and, side by side with theology, there developed a stronger
and more complete philosophy which, chiefly through the influence of
the Latin Fathers, discarded the last remnants of Neo-Platonism and
Gnosticism, and sought inspiration in the earlier and healthier form of
Among the Greek Fathers of this period are Athanasius of
Alexandria (died 373) and the three Cappadocians, Gregory of
Nyssa (331-394), Basil (died 379), and Gregory Nazianzen
(born 330). These men devoted their energies to the defense of the Church in
the great Trinitarian controversy, as did also Cyril of Alexandria
(died 444) in the controversy with Nestorius concerning the personality
Besides these writers there flourished, towards the end of the
Patristic period, two others who devoted special attention to
philosophy -- Pseudo-Dionysius and St. John of
 On Nemesius, bishop of Emesa (about A.D. 450), and his
relation to St. John Damascene, cf. Domanski, "Die Psychologie des
Nemesius," in Beiträge zur Geschichte der Philosophie des
Mittelalters, Bd. III, Heft I (Munster, 1900). Nemesius' works are
printed by Migne, in the Patr. Graeca, Vol. XL. His most
important treatise was translated under the title, The Nature of
Man, by George Wither, London, 1636.
Pseudo-Dionysius.  The works entitled De Divinis Nominibus,
Theologia Mystica, and De Coelesti et Ecciesiastica
Hierarchia, which were at one time attributed to St. Dionysius the
Areopagite, of whom mention is made in the Acts of the Apostles, are
now universally acknowledged to belong to the end of the fifth century.
They contain the last exposition of Christian Neo-Platonism. The
ineffable superiority of God with respect to the world, the emanations
(processiones) of creatures from God, the arrangement of all
created beings in a scale of gradual descent from God, the final return
of all things to their first source, the return of man to God by means
of contemplative ecstasy -- all these Neo-Platonic elements are
present in the philosophy of Dionysius. There can, however, be no doubt
that Dionysius understood these doctrines in a sense perfectly
compatible with the teaching of the Church. The works of Dionysius, as
well as those of his follower, Maximus Confessor (580-662), were
translated by John Scotus Erigena at the beginning of the Scholastic
 For bibliography, cf. Fessler-Jungmann, op. cit.,
Vol. I, p. 635.
St. John of Damascus (end of the seventh century) composed a
work entitled Fountain of Knowledge (pêgê
gnôseôs) and a treatise De Fide Orthodoxa. In
the former he gives an exposition of Aristotelian dialectic and ontology, or science of being. By some
he is said to be the author of the saying, Philosophy is the handmaid
of theology (ancilla theologiae). The phrase is probably of
later origin. 
 Cf. Stöckl, Lehrbuch, I, 317.
Among the Latin Fathers of this period are to be mentioned St.
Hilary (died 368), St. Ambrose (340-397), and St.
Jerome (346 -420). They belong to the history of theology rather
than to that of philosophy. It was in the writings of St.
Augustine that Patristic philosophy attained the zenith of its
course. Augustine is the greatest as well as the last of the masters of
speculative thought who made it possible for the Patristic age to hand
down to the Middle Ages a complete system of Catholic theology. At the
same time he stands among the foremost of the world's great
Life. Aurelius Augustinus was born at Tagaste, in Numidia, in
the year 354. His father, Patricius, was a pagan; his mother, Monica,
was a most exemplary Christian. At Madaura and at Carthage, whither he
went for the purpose of completing the education begun in his native
city, Augustine was lured into the career of sin which he dercribes in
his Confessions. During this period of his life it seemed to him
that the Manichean sect offered the best solution of the enigma of
existence. Later, however, when, after having completed his education,
he taught rhetoric at Carthage and at Rome, the contradictions in which
he perceived Manicheism to be involved drove him to the Academy, where
he learned to be content with probability in lieu of certainty. There
also he learned to study Plato, and it was Plato who first stirred
within his soul the impulse to rise from the moral degradation into
which he had fallen. To the influence of these studies must be added
the prayers of his mother and the persuasive eloquence of St. Ambrose.
Augustine was baptized in the year 387. After his conversion he devoted
himself to the study of the Scriptures, to the refutation of Manichean
and other heresies, and to the task of instituting a systematic
philosophical inquiry concerning God and the human soul. In 395 he was made bishop of Hippo, in Africa; he died In
430, after thirty-five years of active episcopal administration.
Sources. The principal works of St. Augustine which are of
interest In the study of his philosophy are Contra Academicos Libri
III, Soliloquia, De Immortalitate Animae, De Libero Arbitrio, De
Civitate Dei, Confessiones, Retractationes, and his treatises
against the Manicheans. The treatise entitled Principia
may be genuine, although the treatise Categoriae Decem, which is
usually appended to it, is certainly spurious. 
 Cf. Migne, Patr. Lat., Vols. XXXII ff. To the
bibliography given by Fessler-Jungmann, op. cit., Vol. II, p.
250, add Martin, Saint Augustin (Grands Philosophes
series, Paris, 1901).
General Idea of Philosophy. The central ideas of St. Augustine's
philosophical inquiry are God and the human Soul. "Deum et animam scire
cupio. Nihilne plus? Nihil omnino." "Deus, semper idem, noverim me,
noverim te."  On the problems of the existence of God and the nature
of the soul, all philosophical science -- ethics, physics, dialectic
-- is made to converge. Knowledge which cannot be brought to bear on
the soul, teaching it to love God, is unprofitable; it is the knowledge
which "puffeth up." Far from assenting to the maxim attributed to
Tertullian, -- "Credo quia absurdum," -- Augustine viewed the relation
between faith and reason in the light of the principles which the
Scholastics formulated the maxims, "Credo ut intelligam," "Intelligo ut
credam." He says, for example, in De Praedestinatione
Sanctorum,  "Nullus quippe credit, nisi prius cogitaverit esse
credendum," and in De Vera Religione,  "Nostrum est
considerare quibus vel hominibus vel libris credendum sit." St.
Augustine, however, does not define accurately the relations between
philosophy and theology;  this was a task reserved for the master
mind of the thirteenth century.
 Soliloquia, 1, 2, and II, 4.
 II, 5.
 XXV, 46.
 Cf. De Vera Religione, XXIV ff.
Theory of Knowledge. In his treatise Contra Academicos,
St. Augustine begins by discussing the possibility of arriving at
certain knowledge. The Academy maintained that a high degree of
probability is the most that the human mind can attain. St. Augustine
refutes this assertion, and proves by the following arguments that
certitude is possible of attainment.
1. Probability supposes certitude; for that is probable which is like
the truth. If there is no truth, there is no probability. 
 Contra Academicos, II.
2. No one can be happy unless he possesses wisdom; for all men desire
wisdom, and no one is happy unless he attains that which he desires. To
deny that wisdom is possible of attainment, is, therefore, to deny that
happiness is possible. 
 Op. cit., III.
3. The alleged inability of man to attain certitude is not founded on
fact. It is not true that the senses are altogether untrustworthy, nor
is it true that thought is utterly dependent on the impressions of the
senses. It would be absurd to suppose that intellect is not more
reliable than sense. 
 De Immortalitate Anima, X.
4. The possibility of arriving at certainty may be proved by positive
argument. For, whatever else is called in question, our own mental
states are beyond the region of doubt. You may doubt whether you are
one or multiple, you may doubt whether you are moving or at rest, but
you cannot doubt that at this moment you think.  You may contend that
I am deceived, but the very fact that I am deceived proves that I
exist. "Quod si fallor, sum!" A man's doubt proves that he exists,
"Quandoquidem etiam si dubitat, vivit." 
 Soliloq., II, 1.
 De Trinitate, X, 14.
This last argument certainly suggests the Cartesian "Cogito, ergo sum."
It must, however, be remembered, that while Descartes, according to the
commonly received view, intended his argument to be a demonstration
(if, indeed, he intended the "Cogito, ergo sum" to be an argument at
all), Augustine intended the "Quod si fallor, sum," to be merely an indirect
refutation of the principles of the Academy, and not a direct
demonstration of the existence of the thinking subject.
Having shown that certainty is possible of attainment, St. Augustine
proceeds to inquire into the conditions of intellectual
knowledge. There are two ways, he says, in which the human mind
arrives at a knowledge of intelligible objects. The first is by rising
from the data of sense to an understanding of the hidden causes of
things, and, ultimately, to a knowledge of Him Who is the Highest
Cause. This is the process of which St. Paul speaks: "Invisibilia Dei
per ea qum facta sunt intellecta conspiciuntur."  The second method
is one of introspection. "Noli foras exire," he says, "in te ipsum
redi; in interiore homine habitat veritas."  The truth is indwelling
in us. The most excellent means of attaining higher intellectual
knowledge is the contemplation and study of our own intellectual life.
For this, purity of heart and the practice of virtue are necessary. The
purer the heart, the freer is the soul from all defilement, and the
more perfectly will the mind mirror truth; for then it will mirror Him
Who is the source of all truth. This leads to the next point in St.
Augustine's theory of knowledge.
 De Genesi ad Litteram, IV, 32.
 De Vera Relig., XXXIX.
God is the source of all truth. This principle is proved as
follows: "In order to know anything as good or beautiful or true, and
to distinguish it from what is not good or beautiful or true, we must
possess a rule, or standard, by which our judgment regarding the object
in question is determined." Our standard, in order to be trustworthy,
must be immutable, and in order to be available, it must be present to
our minds. Such a standard -- absolute, immutable, omnipresent
goodness and truth and beauty -- is God.  In this light, the light of
eternal truth, is all truth known. Whether we rise in contemplation
from the data of sense to the hidden world of intelligible objects, or from an
introspective knowledge of self to a knowledge of higher truths, we do
so in virtue of the illumination which is the light of the glory of
God. In the Word of God, which is the wisdom of the Father, there dwell
the unchangeable essences, the reasons of things (rationes
rerum), the types according to which all things were made. To deny
the existence of these archetypal forms would be to maintain that God
created things irrationally. He, the all-wise Creator, made all things
according to His wisdom, that is, according to the rationes
aeternae indwelling in the Word: "Singula propriis creata sunt
rationibus."  Corresponding to the ectypes in the world of concrete
existence are the prototypes, whose locus is not a separate
intelligible world, but the Divine Wisdom, the Logos, the Son of God.
This, according to St. Augustine, is what Plato, inspired by biblical
teaching, understood by the topos noêtos. 
 De Libero Arbitrio, II, 12, 16 ; cf. Stöckl,
op. cit., I, 293.
 Quaestiones Octoginta Tres, Cap. 46.
 Cf.De Civ. Dei, VIII, II.
God is, therefore, the source of all truth and of all intellectual
light. In Him are the essential types of truth; He it is Who illumines
the ectypes so that from a knowledge of them we may rise to a knowledge
of truth, and He it is Who illumines the soul itself from within, so
that when we turn our thoughts inward on the soul, we may rise in
contemplation to Him Who is the light of the soul, as the sun is the
light of the physical world.
In St. Augustine's theory of knowledge the lines of thought are
undoubtedly Platonic. The Ontologists, however, are mistaken when they
understand the Platonism of St. Augustine to include the doctrine of
immediate intuition of God, or of the divine ideas. When he teaches
that we know the essences of things in rationibus aeternis, he is
careful to point out that we rise from the data of sense or from a
study of our own intellectual life to a knowledge of these essences.
His meaning is that the essences of things could neither be, nor be
known by us, unless they first existed and were known in the mind of
God. That there is a divine element in our knowledge of created
things, St. Thomas as well as St. Augustine maintained. It is God Who
made the objects of our knowledge, Who endowed the mind with the power
whereby it abstracts from the data of sense the necessary and universal
element which is the object of thought, and Who cooperates in the act
of the mind by which the potentially intelligible is rendered actually
intelligible. In this sense does the Word illumine every man that
cometh into the world. It is clear, then, that the Ontologists
exaggerate the divine element in human knowledge when they maintain
that we have immediate intuition of God and of the ideas contained in
the Divine Mind. Such exaggeration was as far from the mind of the
Plato of Christianity as it was from the mind of the great Christian
Aristotle of the thirteenth century. It must be admitted, nevertheless,
that the Platonic form of St. Augustine's teaching lends more favor to
the Ontologist's interpretation than does the Aristotelian form in
which St. Thomas expressed his theory of knowledge. 
 Cf. St. Thomas, Sum. Theol., Ia, LXXXIV, 5, c; St.
Augustine, Quest., LXXXIII, Cap. 46; Piat, Quid Divini
Nostris Ideis Tribuat Divus Thomas (Paris, 1890).
Theology and Cosmology. While admitting the validity of the
teleological argument for the existence of God, as well as that of the
argument from the testimony of conscience,  St. Augustine bases his
whole system of theodicy on the argument derived from the immutability
and permanence of the object of our intellectual knowledge. The
argument is as follows: We know the truth and we strive for the good.
But nothing is true or good in this world of change and imperfection
except in so far as it participates in the absolute truth and goodness
of Him Who never changes. Whoever denies that God exists must be
prepared to maintain that knowledge and virtue have no object. The
existence of God is, therefore, the essential condition of the moral
and intellectual life.
 De Lib. Arbitr., II, 12, 16.
God cannot be comprehended by the human mind. He is above all
predicates and all categories. When, therefore, we speak of Him, we
are nearer to the truth when we say what He is not, than when we say
what He is: when we speak of God we are little children lisping a
language which we do not understand. "Deus melius scitur nesciendo,"
and again, "Venus, enim, cogitatur Deus quam dicitur, et venus est quam
cogitatur." This truly Christian humility in presence of the great
problems of theodicy we shall find to be as characteristic of the great
masters of Scholasticism as it is of the greatest of the Patristic
philosophers. The Fathers and the schoolmen were as willing as any
modern agnostic is to admit the inability of the human mind to grasp
the truth of God's nature and the inadequacy of human language to
express our thoughts about God.
God is immutable, eternal, all-powerful, all-knowing, absolutely devoid
of potentiality or composition. He is form without matter, essence
In his account of the origin of the universe, St. Augustine
maintains that God from all eternity designed to create the world. God
did not create matter, however, until the beginning of time; for before
matter existed, time did not exist. God is the cause of matter as well
as of intelligible being. He made it out of nothing (creation); it did
not proceed from the substance of God (emanation).  Together with
matter all things else were created at the beginning: "Creavit omnia
simul." Creation was the act of an instant, the Mosaic account of the
six days of creation being merely a description of the six orders or
grades of perfection in which things were created. Not all things.
however, were created in the full possession of what came to be called
their specific perfection. Augustine distinctly admits a process of
development, as when, in the treatise entitled De Genesi ad
Litteram, he says: "In semine, ergo, illa omnia
fuerunt primitus, non mole corporeae magnitudinis sed vi potentiaque
causali" (V, 23). Here he is alluding to the seminariae
rationes, of which he speaks elsewhere as destined ("cum data
fuerit opportunitas temporalis et causalis") to develop
(prorumpere) into their proper species. 
 De Civ. Dei, XI, 4 ff.
 Cf. Gonzalez, Historia de la Filosofia (segunda
edición, Madrid, 1886), II, 80.
God is not the author of evil; He merely permits it. The order of the
universe and the gradation of beings require that some things should be
less perfect than others. God would not permit evil if He could not
draw good from it. Moral evil alone is opposed to the Divine Will. 
Man is a microcosmos, a compendium of the universe. He is the only
being that mediates between God and matter; for, while Augustine admits
the existence of ministering angels, he rejects the whole celestial and
terrestrial hierarchy of the Neo-Platonists.
 De Civ. Dei, XI, 17, 18.
Psychology. The soul is simple, immaterial, spiritual. It is
devoid of quantity: it has no extension in space. In his proof of the
immateriality of the soul, St. Augustine has recourse, among other
arguments, to the following, which was formulated before his time by
Plotinus: If the soul were not immaterial, it could not be in all parts
of the body at the same time. Now the soul is in all parts of the body
at the same time, for wherever an impression is made upon the body, the
soul perceives that impression, and it is not part of the soul that
perceives, but the whole ego. Therefore, the soul is immaterial. 
 Ep. CLXVI ad Hieronymum.
The soul is essentially individual: the notion of a universal soul is
absurd. Equally absurd is the doctrine of transmigration; for that
which is immaterial cannot enter into composition with that which is
material and irrational. Mortality is the only bond of kinship between
man and brute. The angel, like man, possesses a body; but the angelic
body is immortal. The brute possesses a mortal body, but the soul of
the brute is irrational. Man is, therefore, unique in this, that he is
an animal rationale mortale.
The arguments which St. Augustine adduces in favor of the
immortality of the soul savor of Platonic influence. They are as
 Soliloq., II, 2 ff.
1. That in which the imperishable exists must be imperishable.
Imperishable truth dwells in the soul. Therefore the soul is
2. The soul is inseparable from reason; for reason and the soul are not
united in space, and it is only in space that separation can take
place. But reason is imperishable, because the principles of reason are
immortal. Therefore the soul cannot perish.
3. The body is animated, that is, endowed with life. The soul, on the
contrary, is life. To maintain, therefore, that the soul could be
deprived of life would be to say that life is not life or that the soul
is not the soul. 
 Cf.superius, pp. 111, 112.
With regard to the origin of the soul, St. Augustine teaches
that the soul of Adam was created at the beginning: "Creavit Deus omnia
simul." At some subsequent time the soul of Adam was united to the
body, not because of any sin on the part of the soul, but because the
soul requires the body. The souls of the descendants of Adam come into
existence at the moment of their union with the body. As to how they
come into existence, whether by an act of creation
(creationism), or by virtue of the generative process by which
the body originates (traducianism), St. Augustine is unable to
 Cf. Stöckl, op. cit., I, 301.
The soul and body together form one substance, -- man. The soul gives
being and species to the body. It acts on the body. The body, however,
has no independent power of acting on the soul: whatever power the body
possesses is conferred on it by the soul itself. Between soul and body
is interposed a subtle element, partaking at the same time of the
material nature of the body and of the spiritual nature of the soul: it
is analogous to light and air. The function of this element is to
mediate between the soul and the organs of the body, and to unite, in
some mysterious manner, soul and body in one substance. 
St. Augustine attaches special importance to the idea of will.
"Voluntas est quippe in omnibus, omnes nihil aliud quam voluntates
sunt."  It is the will that moves the intellect to action, and it is
the element of will in the act of faith that makes faith meritorious.
Free will is the proximate cause of moral evil.
 De Civ. Dei, XIV, 6.
St. Augustine's discussion of free will in its relation to grace and
predestination belongs to the history of theology.
Ethics. The supreme good of man consists in the eternal
contemplation and love of God in the life to come. Here on earth man's
duty is so to act that he may attain the happiness which is reserved
for him beyond the grave. The path of duty is clearly marked out by the
Divine Law. The destiny of the human soul and the law of God are,
therefore, the determinants of moral good.
To fulfill the law, man must practice virtue. Virtue is defined,
"Ars bene recteque vivendi."  Virtue does not imply apathy, as the
Stoics taught: the emotions are not to be destroyed or eradicated, but
to be kept under control and restrained within the limits prescribed by
the Law of God. Now the Law of God is the Law of Love. Man should love God above all things; he should love
himself with a rational love, seeking what is best and doing what is
best for himself in the light of his eternal destiny; he should love
his fellow-man, desiring what is best for him and aiding him to attain
it. Charity, therefore, which is love, is the foundation of all virtue:
on this foundation are built prudence, fortitude, temperance, and
 Op. cit., XIV, 9.
 Cf. Stökl, op. cit., 1, 306; English trans., p.
Historical Position. Even from this summary sketch of the
philosophy of St. Augustine it is possible to glean something of the
vastness of his system of speculative thought. His inquiries cover the
whole range of speculation; he synthesizes the best elements of pagan
philosophy into a system of Christian thought; and wherever his
inquiries lead him he exhibits that spirit of coherent system, that
perfect grasp of his subject, that sublimity of thought and language
which distinguish him among all the philosophers of Christian times as
the Plato of Christianity. And when we remember that St. Augustine was
as distinguished among theologians as he was among philosophers, we
realize that his was a mind almost superhuman in its transcendent power
The debt which philosophy owes to St. Augustine includes, besides many
original contributions to the definition of the Christian concept of
God, of the human soul, and of the destiny and duty of man, the first
essay on the part of a Christian philosopher to discover and expound
the philosophy of human history. In the treatise De Civitate Dei
he appears as the exponent of the "law of progress which governs the
history of humanity, and of which even those who fight against it
become instruments in the hands of Providence according to the Divine
 Cf.De Civ. Dei, I, 8.
It is scarcely necessary to call attention to the preponderance of the
influence of Plato on the philosophic thought of St. Augustine. Like
all the other Fathers of the Church, St. Augustine
esteemed Plato more highly than Aristotle. The latter he styled "Vir
excellentis ingenii, et Platoni quidem impar, sed multos facile
superans."  Although, however, the era of Christian Platonism
virtually came to an end with Augustine, the Scholastic era, in which
the importance of Aristotle grew until it reached its maximum in the
thirteenth century, was not oblivious of the debt which Christianity
and philosophy owe to the man who first Christianized the teachings of
 De Civ. Dei. VIII, 12.
The period between the death of St. Augustine and the rise of
Scholasticism is one of comparatively little intellectual activity.
Throughout Europe, men like Claudianus Mamertus (middle of fifth
century), Boethius (470-526), Cassiodorus (468-575),
St. Isidore of Seville (seventh century), and Venerable
Bede (674-735) labored merely to preserve what the past had
bequeathed and to transmit the legacy to times more favorable for the
growth and development of Christian speculation. 
 Cf. Stewart, Boethius (London, 1891).
Retrospect. Patristic philosophy exhibits all the
characteristics of the age to which it belonged, -- the era of the
struggle and triumph of Christianity and of the first adjustment of
Christian thought to pagan civilization and culture. To the period of
struggle belongs the work of the Apologists; to the first centuries of
triumph belong the earliest constructive attempts of the Alexandrian
school; while to the later centuries of the period intervening between
the triumph of Christianity and the invasion of the barbarians belongs
St. Augustine's systematic effort to harmonize Christian teaching with
the greatest achievements of pagan thought. After the time of St.
Augustine, the condition of Christian Europe was not favorable to
speculation, and it was not until the dawn of the era of Neo-Latin
civilization that in new circumstances, and in a different social and
political climate, the schoolmen completed the task begun by the
Fathers. Patristic philosophy is fragmentary and devoid of
unity. It belongs to an epoch in which everything except religion was
decadent and in which religion itself, though vigorous, had not yet
succeeded in infusing the Christian ideal into the life and thought of
Europe. Scholastic philosophy will begin with the opening of the new
era; it will grow into the new life of Christianized Europe, and will
attain the golden age of its development whenever and wherever the
ideal of the Christian life shall have transformed the social and
political conditions into an atmosphere most congenial to Christian
speculation. The Fathers defined, at least provisionally, the
intellectual basis of the dogmatic system of the Church; they protested
successfully against the gnostic, which was in reality the
rationalistic, subordination of revelation to reason, and they stated
the question which Scholastic philosophy took up and answered: How can
reason and revelation be shown to be distinct and, at the same time,
consistent sources of truth?