The power of generalizing and of forming abstract ideas exists, or at least is exercised, in varying degrees among different races and at different times. The peculiar feature of the intellectual history of the Greeks is the rapidity with which the power was developed, and the strength of the grasp which it had upon them.

The elaboration of one class of such ideas, those of form and quantity, led to the formation of a group of sciences, the mathematical sciences, which hold a permanent place. The earliest and most typical of these sciences is geometry. In it, the attention is drawn away from all the other characteristics of material things, and fixed upon the single characteristic of their form. The forms are regarded in themselves. The process of abstraction or analysis reaches its limit in the point, and from that limit the mind, making a new departure, begins the process of construction or synthesis. Complex ideas are formed by the addition of one simple idea to another, and having been so formed can be precisely defined. Their constituent elements can be distinctly stated, and a clear boundary drawn round the whole. They can be so marked off from other ideas that the idea which one man has formed can be communicated to and represented in another man’s mind. The inferences which, assuming certain “axioms” to be true and certain “postulates” to be granted, are made by one man, are accepted by another man or at once disproved. There is no question of mere probability, nor any halting between two opinions. The inferences are not only true but certain.

The result is, that there are not two sciences of geometry, but one: all who study it are agreed as to both its definitions and its inferences.

The elaboration of another class of abstract ideas, those of quality, marched at first by a parallel road. To a limited extent such a parallel march is possible. The words which are used to express sensible qualities suggest the same ideas to different minds. They are applied by different minds to the same objects. But the limits of such an agreement are narrow. When we pass from the abstract ideas of qualities, or generalizations as to substances, which can be tested by the senses, to such ideas as those, for example, of courage or justice, law or duty, though the words suggest, on the whole, the same ideas to one man as to another, not all men would uniformly apply the same words to the same actions. The phenomena which suggest such ideas assume a different form and colour as they are regarded from different points of view. They enter into different combinations. They are not sharply marked out by lines which would be universally recognized. The attention of different men is arrested by different features. There is consequently no universally recognized definition of them. Nor is such a definition possible. The ideas themselves tend to shade off into their contraries. There is a fringe of haze round each of them. The result is that assertions about them vary. There is not one system of philosophy only; there are many.

Between these two classes of generalizations and abstractions, those of quantity and those of quality or substance, many Greek thinkers do not appear to have made any clear distinction. Ideas of each class were regarded as equally capable of being defined; the canons of inference which were applicable to the one were conceived to be equally applicable to the other: and the certainty of inference and exactness of demonstration which were possible in regard to the ideal forms of geometry, were supposed to be also possible in regard to the conceptions of metaphysics and ethics.[204]

The habit of making definitions, and of drawing deductions from them, was fostered by the habit of discussion. Discussion under the name of dialectic, which implies that it was but a regulated conversation, had a large place, not only in the rhetorical and philosophical schools, but also in ordinary Greek life. It was like a game of cards. The game, so to speak, was conducted under strict and recognized rules; but it could not proceed unless each card had a determined and admitted value. The definition of terms was its necessary preliminary; and dialectic helped to spread the habit of requiring definitions over a wider area and to give it a deeper root.

There was less divergence in the definitions themselves than there was in the propositions that were deduced from them. That is to say, there was a verbal agreement as to definitions which was not a real agreement of ideas: the same words were found on examination to cover different areas of thought. But whether the difference lay in the definitions themselves or in the deductions made from them, there was nothing to determine which of two contrary or contradictory propositions was true. There was no universally recognized standard of appeal, or criterion, as it was termed. Indeed, the question of the nature of the criterion was one of the chief questions at issue. Consequently, assertions about abstract ideas and wide generalizations could only be regarded as the affirmations of a personal conviction. The making of such an affirmation was expressed by the same phrase which was used for a resolution of the will—“It seems to me,” or “It seems (good) to me” (δοκεῖ μοι): the affirmation itself, by the corresponding substantive, dogma (δόγμα). But just as the resolutions of the will of a monarch were obeyed by his subjects, that is, were adopted as resolutions of the will of other persons, so the affirmations of a thinker might be assented to by those who listened to him, that is, might become affirmations of other persons. In the one case as in the other, the same word dogma was employed.[205] It thus came to express (1) a decree, (2) a doctrine. The latter use tended to predominate. The word came ordinarily to express an affirmation made by a philosopher which was accepted as true by those who, from the fact of so accepting it, became his followers and formed his school. The acquiescence of a large number of men in the same affirmation gave to such an affirmation a high degree of probability; but it did not cause it to lose its original character of a personal conviction, nor did it afford any guarantee that the coincidence of expression was also a coincidence of ideas either between the original thinker and his disciples, or between the disciples themselves.[206]

Within these limits of its original and proper use, and as expressing a fact of mind, the word has an indisputable value. But the fact of the personal character of a dogma soon became lost to sight. Two tendencies which grew with a parallel growth dominated the world in place of the recognition of it. It came to be assumed that certain convictions of certain philosophers were not simply true in relation to the philosophers themselves, and to the state of knowledge in their time, but had a universal validity: subjective and temporary convictions were thus elevated to the rank of objective and eternal truths. It came also to be assumed that the processes of reason so closely followed the order of nature, that a system of ideas constructed in strict accordance with the laws of reasoning corresponded exactly with the realities of things. The unity of such a system reflected, it was thought, the unity of the world of objective fact. It followed that the truth or untruth of a given proposition was thought to be determined by its logical consistency or inconsistency with the sum of previous inferences.

These tendencies were strongly accentuated by the decay of original thinking. Philosophy in later Greece was less thought than literature. It was the exegesis of received doctrines. Philosophers had become professors. The question of what was in itself true had become entangled with the question of what the Master had said. The moral duty of adherence to the traditions of a school was stronger than the moral duty of finding the truth at all hazards. The literary expression of a doctrine came to be more important than the doctrine itself. The differences of expression between one thinker and another were exaggerated. Words became fetishes. Outside the schools were those who were littérateurs rather than philosophers, and who fused different elements together into systems which had a greater unity of literary form than of logical coherence. But these very facts of the literary character of philosophy, and of the contradictions in the expositions of it, served to spread it over a wider area. They tended on the one hand to bring a literary acquaintance with philosophy into the sphere of general education, and on the other hand to produce a propaganda. Sect rivalled sect in trying to win scholars for its school. The result was that the ordinary life of later Greece was saturated with philosophical ideas, and that the discordant theories of rival schools were blended together in the average mind into a syncretistic dogmatism.

Against this whole group of tendencies there was more than one reaction. The tendency to dogmatize was met by the tendency to doubt; and the tendency to doubt flowed in many streams, which can with difficulty be traced in minute detail, but whose general course is sufficiently described for the ordinary student in the Academics of Cicero. In the second and third centuries of our era there had come to be three main groups of schools. “Some men,” writes Sextus Empiricus,[207] “say that they have found the truth; some say that it is impossible for truth to be apprehended; some still search for it. The first class consists of those who are specially designated Dogmatics, the followers of Aristotle and Epicurus, the Stoics, and some others: the second class consists of the followers of Clitomachus and Carneades, and other Academics: the third class consists of the Sceptics.” They may be distinguished as the philosophy of assertion, the philosophy of denial, and the philosophy of research.[208] But the first of these was in an overwhelming majority. The Dogmatics, especially in the form either of pure Stoicism or of Stoicism largely infused with Platonism, were in possession of the field of educated thought. It is a convincing proof of the completeness with which that thought was saturated with their methods and their fundamental conceptions, that those methods and conceptions are found even among the philosophers of research who claimed to have wholly disentangled themselves from them.[209]

The philosophy of assertion, the philosophy of denial, and the philosophy of research, were all alike outside the earliest forms of Christianity. In those forms the moral and spiritual elements were not only supreme but exclusive. They reflected the philosophy, not of Greece, but of Palestine. That philosophy was almost entirely ethical. It dealt with the problems, not of being in the abstract, but of human life. It was stated for the most part in short antithetical sentences, with a symbol or parable to enforce them. It was a philosophy of proverbs. It had no eye for the minute anatomy of thought. It had no system, for the sense of system was not yet awakened. It had no taste for verbal distinctions. It was content with the symmetry of balanced sentences, without attempting to construct a perfect whole. It reflected as in a mirror, and not unconsciously, the difficulties, the contradictions, the unsolved enigmas of the world of fact.

When this Palestinian philosophy became more self-conscious than it had been, it remained still within its own sphere, the enigmas of the moral world were still its subject-matter, and it became in the Fathers of the Talmud on the one hand fatalism, and on the other casuistry.

The earliest forms of Christianity were not only outside the sphere of Greek philosophy, but they also appealed, on the one hand, mainly to the classes which philosophy did not reach, and, on the other hand, to a standard which philosophy did not recognize. “Not many wise men after the flesh” were called in St. Paul’s time: and more than a century afterwards, Celsus sarcastically declared the law of admission to the Christian communities to be—“Let no educated man enter, no wise man, no prudent man, for such things we deem evil; but whoever is ignorant, whoever is unintelligent, whoever is uneducated, whoever is simple, let him come and be welcome.”[210] It proclaimed, moreover, that “the philosophy of the world was foolishness with God.” It appealed to prophecy and to testimony. “Instead of logical demonstration, it produced living witnesses of the words and wonderful doings of Jesus Christ.” The philosophers from the point of view of “worldly education” made sport of it: Celsus[211] declared that the Christian teachers were no better than the priests of Mithra or of Hekaté, leading men wherever they willed with the maxims of a blind belief.

It is therefore the more remarkable that within a century and a half after Christianity and philosophy first came into close contact, the ideas and methods of philosophy had flowed in such mass into Christianity, and filled so large a place in it, as to have made it no less a philosophy than a religion.

The question which arises, and which should properly be discussed before the influences of particular ideas are traced in particular doctrines, is, how this result is to be accounted for as a whole. The answer must explain both how Christianity and philosophy came into contact, and how when in contact the one exercised upon the other the influence of a moulding force.

The explanation is to be found in the fact that, in spite of the apparent and superficial antagonism, between certain leading ideas of current philosophy and the leading ideas of Christianity there was a special and real kinship. Christianity gave to the problems of philosophy a new solution which was cognate to the old, and to its doubts the certainty of a revelation. The kinship of ideas is admitted, and explanations of it are offered by both Christian writers and their opponents. “We teach the same as the Greeks,” says Justin Martyr,[212] “though we alone are hated for what we teach.” “Some of our number,” says Tertullian,[213] “who are versed in ancient literature, have composed books by means of which it may be clearly seen that we have embraced nothing new or monstrous, nothing in which we have not the support of common and public literature.” Elsewhere[214] the same writer founds an argument for the toleration of Christianity on the fact that its opponents maintained it to be but a kind of philosophy, teaching the very same doctrines as the philosophers—innocence, justice, endurance, soberness, and chastity: he claims on that ground the same liberty for Christians which was enjoyed by philosophers.

The general recognition of this kinship of ideas is even more conclusively shown by the fact that explanations of it were offered on both the one side and the other.

(a) It was argued by some Christian apologists that the best doctrines of philosophy were due to the inworking in the world of the same Divine Word who had become incarnate in Jesus Christ. “The teachings of Plato,” says Justin Martyr,[215] “are not alien to those of Christ, though not in all respects similar.... For all the writers (of antiquity) were able to have a dim vision of realities by means of the indwelling seed of the implanted Word.” It was argued by others that philosophers had borrowed or “stolen” their doctrines from the Scriptures. “From the divine preachings of the prophets,” says Minucius Felix,[216] “they imitated the shadow of half-truths.” “What poet or sophist,” says Tertullian,[217] “has not drunk at the fountain of the prophets? From thence it is, therefore, that philosophers have quenched the thirst of their minds, so that it is the very things which they have of ours which bring us into comparison with them.” “They have borrowed from our books,” says Clement of Alexandria,[218] “the chief doctrines they hold, both on faith and knowledge and science, on hope and love, on repentance and temperance and the fear of God:” and he goes in detail through many doctrines, speculative as well as ethical, either to show that they were borrowed from revelation, or to uphold the truer thesis that philosophy was no less the schoolmaster of the Greeks than the Law was of the Jews to bring them to Christ.

(b) It was argued, on the other hand, by the opponents of Christianity that it was a mere mimicry of philosophy or a blurred copy of it. “They weave a web of misunderstandings of the old doctrine,” says Celsus,[219] “and sound them forth with a loud trumpet before men, like hierophants booming round those who are being initiated in mysteries.” Christianity was but a misunderstood Platonism. Whatever in it was true had been better expressed before.[220] Even the striking and distinctive saying of the Sermon on the Mount, “Whosoever shall smite thee on thy right cheek, turn to him the other also,” was but a coarser and more homely way of saying what had been extremely well said by Plato’s Socrates.[221]

It was through this kinship of ideas that Christianity was readily absorbed by some of the higher natures in the Greek world. The two classes of ideas probably came into contact in philosophical Judaism. For it is clear on the one hand that the Jews of the dispersion had a literature, and on the other hand that that literature was clothing itself in Greek forms and attracting the attention of the Greek world. Some of that literature was philosophical. In the Sibylline verses, the poem of Phocylides, and the letters of Heraclitus, there is a blending of theology and ethics: in some of the writings which are ascribed to Philo, but which in reality bridge the interval between Philo and the Christian Fathers, there is a blending of theology and metaphysics. None of them are “very far from the kingdom of God.” The hypothesis that they paved the way for Christian philosophy is confirmed by the fact that in the first articulate expressions of that philosophy precisely those elements are dominant which were dominant in Jewish philosophy. Two such elements may specially be mentioned: (1) the allegorical method of interpretation which was common to both Jews and Greeks, and by means of which both the Gnostics who were without, and the Alexandrians who were within, the pale of the associated communities, were able to find their philosophy in the Old Testament as well as in the New; (2) the cosmological speculations, which occupied only a small space in the thoughts of earlier Greek thinkers, but which were already widening to a larger circle on the surface of Greek philosophy, and which became so prominent in the first Christian philosophies as to have thrust aside almost all other elements in the current representations of them.

The Christian philosophy which thus rose out of philosophical Judaism was partly apologetic and partly speculative. The apologetic part of it arose from the necessity of defence. The educated world tended to scout Christianity when it was first presented to them, as an immoral and barbarous atheism. It was necessary to show that it was neither the one nor the other. The defence naturally fell into the hands of those Christians who were versed in Greek methods; and they not less naturally sought for points of agreement rather than of difference, and presented Christian truths in a Greek form. The speculative part of it arose from some of its elements having found an especial affinity with some of the new developments of Pythagoreanism and Platonism. Inside the original communities were men who began to build great edifices of speculation upon the narrow basis of one or other of the pinnacles of the Christian temple; and outside those communities were men who began to coalesce into communities which had the same moral aims as the original communities, and which appealed in the main to the same authorities, but in which the simpler forms of worship were elaborated into a thaumaturgic ritual, and the solid facts of Scripture history evaporated into mist. They were linked on the one hand with the cults of the Greek mysteries, and on the other with philosophical idealism. The tendency to conceive of abstract ideas as substances, with form and real existence, received in them its extreme development. Wisdom and vice, silence and desire, were real beings: they were not, as they had been to earlier thinkers, mere thin vapours which had floated upwards from the world of sensible existences, and hung like clouds in an uncertain twilight. The real world was indeed not the world of sensible existences, of thoughts and utterances about sensible things, but a world in which sensible existences were the shadows and not the substance, the waves and not the sea.[222]

It was natural that those who held to the earlier forms of Christianity should take alarm. “I am not unaware,” says Clement of Alexandria, in setting forth the design of his Stromateis,[223] “of what is dinned in our ears by the ignorant timidity of those who tell us that we ought to occupy ourselves with the most necessary matters, those in which the Faith consists: and that we should pass by the superfluous matters that lie outside them, which vex and detain us in vain over points that contribute nothing to the end in view. There are others who think that philosophy will prove to have been introduced into life from an evil source, at the hands of a mischievous inventor, for the ruin of men.” “The simpler-minded,” says Tertullian,[224] “not to say ignorant and unlearned men, who always form the majority of believers, are frightened at the Economy” [the philosophical explanation of the doctrine of the Trinity]. “These men,” says a contemporary writer,[225] of some of the early philosophical schools at Rome, “have fearlessly perverted the divine Scriptures, and set aside the rule of the ancient faith, and have not known Christ, seeking as they do, not what the divine Scriptures say, but what form of syllogism may be found to support their godlessness; and if one advances any express statement of the divine Scripture, they try to find out whether it can form a conjunctive or a disjunctive hypothetical. And having deserted the holy Scriptures of God, they study geometry, being of the earth and speaking of the earth, and ignoring Him who comes from above. Some of them, at any rate, give their minds to Euclid: some of them are admiring disciples of Aristotle and Theophrastus: as for Galen, some of them go so far as actually to worship him.”

The history of the second century is the history of the clash and conflict between these new mystical and philosophical elements of Christianity and its earlier forms. On the one hand were the majority of the original communities, holding in the main the conception of Christianity which probably finds its best contemporary exposition in the first two books of the Apostolical Constitutions, a religion of stern moral practice and of strict moral discipline, of the simple love of God and the unelaborated faith in Jesus Christ. On the other hand were the new communities, and the new members of the older communities, with their conception of knowledge side by side with faith, and with their tendency to speculate side by side with their acceptance of tradition. The conflict was inevitable. In the current state of educated opinion it would have been as impossible for the original communities to ignore the existence of philosophical elements either in their own body, or in the new communities which were growing up around them, as it would be for the Christian churches of our own day to ignore physical science. The result of the conflict was, that the extreme wing of each of the contending parties dropped off from the main body. The old-fashioned Christians, who would admit of no compromise, and maintained the old usages unchanged, were gradually detached as Ebionites, or Nazaræans. The old orthodoxy became a new heresy. In the lists of the early hand-books they are ranked as the first heretics. The more philosophical Gnostics also passed one by one outside the Christian lines. Their ideas gradually lost their Christian colour. They lived in another, but non-Christian, form. The true Gnostic, though he repudiates the name, is Plotinus. The logical development of the thoughts of Basilides and Justin, of Valentinus and the Naassenes, is to be found in Neo-Platonism—that splendid vision of incomparable and irrecoverable cloudland in which the sun of Greek philosophy set.

The struggle really ended, as almost all great conflicts end, in a compromise. There was apparently so complete a victory of the original communities and of the principles which they embodied, that their opponents seem to vanish from Christian literature and Christian history. It was in reality a victory in which the victors were the vanquished. There was so large an absorption by the original communities of the principles of their opponents as to destroy the main reason for a separate existence. The absorption was less of speculations than of the tendency to speculate. The residuum of permanent effect was mainly a certain habit of mind. This is at once a consequence and a proof of the general argument which has been advanced above, that certain elements of education in philosophy had been so widely diffused, and in the course of centuries had become so strongly rooted, as to have caused an instinctive tendency to throw ideas into a philosophical form, and to test assertions by philosophical canons. The existence of such a tendency is shown in the first instance by the mode in which the earliest “defenders of the faith” met their opponents; and the supposition that it was instinctive is a legitimate inference from the fact that it was unconscious. For Tatian,[226] though he ridicules Greek philosophy and professes to have abandoned it, yet builds up theories of the Logos, of free-will, and of the nature of spirit, out of the elements of current philosophical conceptions. Tertullian, though he asks,[227] “What resemblance is there between a philosopher and a Christian, between a disciple of Greece and a disciple of heaven?” expresses Christian truths in philosophical terms, and argues against his opponents—for example, against Marcion—by methods which might serve as typical examples of the current methods of controversy between philosophical schools. And Hippolytus,[228] though he reproves another Christian writer for listening to Gentile teaching, and so disobeying the injunction, “Go not into the way of the Gentiles,” is himself saturated with philosophical conceptions and philosophical literature.

The answer, in short, to the main question which has been before us is that Christianity came into a ground which was already prepared for it. Education was widely diffused over the Greek world, and among all classes of the community. It had not merely aroused the habit of inquiry which is the foundation of philosophy, but had also taught certain philosophical methods. Certain elements of the philosophical temper had come into existence on a large scale, penetrating all classes of society and inwrought into the general intellectual fibre of the time. They had produced a certain habit of mind. When, through the kinship of ideas, Christianity had been absorbed by the educated classes, the habit of mind which had preceded it remained and dominated. It showed itself mainly in three ways:

1. The first of these was the tendency to define. The earliest Christians had been content to believe in God and to worship Him, without endeavouring to define precisely the conception of Him which lay beneath their faith and their worship. They looked up to Him as their Father in heaven. They thought of Him as one, as beneficent, and as supreme. But they drew no fence of words round their idea of Him, and still less did they attempt to demonstrate by processes of reason that their idea of Him was true. But there is an anecdote quoted with approval by Eusebius[229] from Rhodon, a controversialist of the latter part of the second century, which furnishes a striking proof of the growing strength at that time of the philosophical temper. It relates the main points of a short controversy between Rhodon and Apelles. Apelles was in some respects in sympathy with Marcion, and in some respects followed the older Christian tradition. He refused to be drawn into the new philosophizing current; and Rhodon attacked him for his conservatism. “He was often refuted for his errors, which indeed made him say that we ought not to inquire too closely into doctrine; but that as every one had believed, so he should remain. For he declared that those who set their hopes on the Crucified One would be saved, if only they were found in good works. But the most uncertain thing of all that he said was what he said about God. He held no doubt that there is One Principle, just as we hold too: but when I said to him, ‘Tell us how you demonstrate that, or on what grounds you are able to assert that there is One Principle,’ ... he said that he did not know, but that that was his conviction. When I thereupon adjured him to tell the truth, he swore that he was telling the truth, that he did not know how there is one unbegotten God, but that nevertheless so he believed. Then I laughed at him and denounced him, for that, giving himself out to be a teacher, he did not know how to prove what he taught.”

2. The second manifestation of the philosophical habit of mind was the tendency to speculate, that is, to draw inferences from definitions, to weave the inferences into systems, and to test assertions by their logical consistency or inconsistency with those systems. The earliest Christians had but little conception of a system. The inconsistency of one apparently true statement with another did not vex their souls. Their beliefs reflected the variety of the world and of men’s thoughts about the world. It was one of the secrets of the first great successes of Christianity. There were different and apparently irreconcilable elements in it. It appealed to men of various mould. It furnished a basis for the construction of strangely diverse edifices. But the result of the ascendency of philosophy was, that in the fourth and fifth centuries the majority of churches insisted not only upon a unity of belief in the fundamental facts of Christianity, but also upon a uniformity of speculations in regard to those facts. The premises of those speculations were assumed; the conclusions logically followed: the propositions which were contrary or contradictory to them were measured, not by the greater or less probability of the premises, but by the logical certainty of the conclusions; and symmetry became a test of truth.

3. The new habit of mind manifested itself not less in the importance which came to be attached to it. The holding of approved opinions was elevated to a position at first co-ordinate with, and at last superior to, trust in God and the effort to live a holy life. There had been indeed from the first an element of knowledge in the conception of the means of salvation. The knowledge of the facts of the life of Jesus Christ necessarily precedes faith in him. But under the touch of Greek philosophy, knowledge had become speculation: whatever obligation attached to faith in its original sense was conceived to attach to it in its new sense: the new form of knowledge was held to be not less necessary than the old.

The Western communities not only took over the greater part of the inheritance, but also proceeded to assume in a still greater degree the correspondence of ideas with realities, and of inferences about ideas with truths about realities. It added such large groups to the sum of them, that in the dogmatic theology of Latin and Teutonic Christendom the content is more Western than Eastern. But the conception of such a theology and its underlying assumptions are Greek. They come from the Greek tendency to attach the same certainty to metaphysical as to physical ideas. They are in reality built upon a quicksand. There is no more reason to suppose that God has revealed metaphysics than that He has revealed chemistry. The Christian revelation is, at least primarily, a setting forth of certain facts. It does not in itself afford a guarantee of the certainty of the speculations which are built upon those facts. All such speculations are dogmas in the original sense of the word. They are simply personal convictions. To the statement of one man’s convictions other men may assent: but they can never be quite sure that they understand its terms in the precise sense in which the original framer of the statement understood them.

The belief that metaphysical theology is more than this, is the chief bequest of Greece to religious thought, and it has been a damnosa hereditas. It has given to later Christianity that part of it which is doomed to perish, and which yet, while it lives, holds the key of the prison-house of many souls.