Robertson, D.W. Jr. "GENERAL INTRODUCTION I. Medieval Life and Ideals". The Literature of Medieval England. New York: McGraw-Hill, 1970: 1-9
Facing page: Très riches heures du Duc de Berry. A warm hearth in February.
The period of European history extending from the last days of classical antiquity to the Renaissance of the fifteenth century is known as "the Middle Ages"-the ages in between-as though these ages constituted a kind of interregnum between the classical world and what is thought of as a revival of classical traditions in modern times. Thus the philosopher Hegel characterized the period as one of "infinite falsehood" marked by the isolation and subservience of the individual and by the "gradual secularization" of the Church. In a more popular sense, the word medieval is still used frequently to describe harsh, oppressive, or superstitious practices. Most of us are therefore prepared to assume offhand that the Middle Ages marked an unproductive period from which humanity is fortunate to have escaped. However, recent historians have begun to discover that the break between antiquity and the Middle Ages, especially in intellectual and cultural development, was not so sharp as was once thought and that, moreover, the decisive beginnings of the modern world are to be found, not in the Renaissance, but in the mid-eighteenth century. With these newer perspectives there has come a revival of interest in medieval culture, an interest' inspired not so much by the romantic nostalgia that made knights and their ladies favorite subjects of nineteenth-century romance, but by a genuine desire for understanding.
However we may characterize them, the thousand years of the Middle Ages form a rich and varied chapter in human history. The unsettled social conditions of the early years of the period, marked by the gradual economic and political collapse of the Roman Empire and by the success of barbarian invasions, left the task of maintaining cultural traditions to the Church. Monastic centers were islands of civilization in a chaotic world of economic collapse and warfare. As time passed, a new form of social organization, known as feudalism, gradually developed to replace the family, tribal, and warrior groups of the barbarians. During the eleventh and twelfth centuries feudal society rapidly developed its own ideals, consistent with the hierarchical patterns of Patristic theology and reinforced by the ethical doctrines of late classical philosophy, especially as those doctrines were found explicitly in the writings of Cicero and Seneca and implicitly in the writings of Virgil, Horace, and Ovid. Among philosophical writings, The Consolation of Philosophy of Boethius exerted a profound and continuous influence. The Church gradually spread its civilizing disciplines beyond the mona5teries, which began to be replaced as centers of learning by cathedral schools. Some of these schools became universities, and one of them, at Paris, became the center of European culture. Toward the close of the period, feudal ideals came to be supplemented by a more nationalistic spirit, trade and commerce contributed to the rapid growth and relative prosperity of cities, and, by the fifteenth century, the merchant classes were beginning to assert a culture of their own, still basically religious in outlook, but nevertheless different in taste and attitude from the more aristocratic culture of the past. The break with the aristocratic traditions of the past was not completed,' however, until the French Revolution, and we should not seek modern attitudes toward the individual or toward society in medieval writings. There is some truth in the assertion that the rococo style marks the last flowering of a tradition that extends from antiquity without fundamental upheaval throughout the Middle Ages and the Renaissance. In any event, the Middle Ages can hardly be called a period of stagnation, a mere lapse between Athens and Washington.
From a sociological point of view, medieval men tended to bond themselves together in small, tightly knit groups, most of which preserved the hierarchical structure of the patriarchal family. To a certain extent, this development may be said to have begun in late antiquity, when the country villas of wealthy Romans throughout the empire, having been cut off by inflation and heavy taxation from the cities, frequently became independent and self-supporting. The Germanic barbarians, meanwhile, formed themselves into small military units somewhat resembling the commitatus described by Tacitus in the Germania. These groups were originally bound by blood relationships, but in the course of time military leaders began to acquire followers from alien families bound to them by personal contractual obligations designed to perpetuate the kind of integrity that rested originally on family ties. Later on, feudal holdings supported groups bound by ties of homage and fidelity to a noble overlord. When merchants began to flourish in urban centers, they formed guilds or confraternities, which were not trade unions in the modern sense, but groups of men, some poor and some wealthy, banded together in a restricted area by virtue of a common interest in a trade or craft. Typically, such guilds originally developed from parish fraternities centered in local parish churches. Meanwhile, there were fraternities of other kinds, not associated with any special trade, and in the country the parish church frequently served as a center for community life. The prosperous craftsman in the city might have living in his house a number of servants, journeymen, or apprentices, who, like his own wife and children, formed a part of his familia or household, and to whom he acted as a father as well as a master. For the most part, industrial work was carried on in households of this kind. The master's house was his shop; his workers sat at his table and slept under his roof.
This fragmentation of society into small units, largely familial in structure, constitutes what Hegel called "isolation"; but, as modern sociologists inform us, although small groups may be isolated to a certain extent from one another and may come into conflict at times, they serve to prevent the isolation of the individual who belongs to them. During the Middle Ages, most men, except during dislocations arising from war or pestilence, enjoyed a more or less natural place in their communities. Young boys could readily see their elders at work, knew what they did, and were not puzzled about their own identity as members of the community. In this situation a mans interests were naturally centered on the welfare of his group, which was, in effect, a part o f x s own identity. The behavior of the other members of the group to which he belonged was a matter of vital interest to him, since the effects of that behavior on his own welfare were immediately apparent. Group behavior, however, is a moral rather than a psychological problem. It was natural, therefore, that medieval men should think in moral terms, whereas we today, as members of large amorphous groups not based on close personal relationships, are likely to think of our problems as being personal or psychological.
However isolated medieval social groups may have been from one another, and however frequently they may have come in conflict with each other, in feudal warfare, in clashes among guilds, or in other ways, they were united by a common set of Christian beliefs and by a common interest in the larger community of the Church. Here they shared not only a mutual respect for the Word of God, but also, especially after the end of the twelfth century, a mutual participation in the sacraments. The fact that men were professed Christians, however, did not mean that they were necessarily moral in their behavior, nor that they were hypocrites or pagans if they were not moral. Medieval Christian doctrine readily acknowledged that Christ came for the benefit of sinners, not for the sake of the virtuous. N o man was thought to be free from the stain of sin. One of the decrees of the great Lateran Council of 1215 stipulated that every individual among the adult faithful should go to confession before his parish priest at least once a year, the assumption being that he would have need to reveal a considerable number of "deadly" sins accumulated during a years time, no matter how virtuous he might be. The whole point of the New Law, or the message of the New Testament, was felt to be that mercy is available through Christ to all those who are truly penitent. The Old Law, it was said, told men what not to do, but offered no relief from the almost impossible task of obeying all its admonitions. The New Law provided an opportunity to love God and ones fellow man in such a way that contrition might follow violation of the moral law. Medieval Christianity was a religion of love, not of righteousness.
At the same time, however, the "love of ones neighbor had nothing in common with" the brotherhood of man," an ideal popularized both by Christian thinkers and by secular philosophers during the nineteenth century. The fact of humanity was not regarded as an excuse for errant behavior, nor as a predicament beset by ambiguity and potential irrationality. It implied, on the contrary, an obligation to act reasonably. Medieval society, as it developed, became hierarchical in structure, and it was widely recognized that some men were more lovable, or more reasonable, than others. Vicious men were not thought of as being merely bestial, but as worse than bestial, since a beast has no reason to corrupt. We should not, therefore, expect democratic or humanitarian sentiments among medieval authors. Such sentiments were not promulgated by medieval theologians and would certainly have found small sympathy among the medieval nobility.
It cannot be emphasized too strongly, however, that the New Law, frequently expressed as "justice tempered with mercy," or as the love of "common profit, "as contrasted with self-love or malice, was a social and political as well as a theological ideal. King Alfred introduced his laws with the Ten Commandments followed by the two Precepts of Charity, feudal lords of all ranks were urged to temper justice with mercy in the treatment of their subjects, vassals were admonished to love their overlords, university colleges were theoretically unified in charity, and even Italian cities were described as communities held together by a bond of charity. The problem of whether or not this ideal was observed, as in the nature of things it frequently was not, was of urgent practical importance to men in all walks of life. Tyranny and oppression in any medieval community, from the hierarchy of the kingdom to the domestic hierarchy of the family, were associated with the Old Law, the malice of which was considered natural to fallen man. It is hardly surprising, therefore, that contrasts between the Old Law and the New should have been one of the most characteristic themes of medieval art and literature. The theme is by no means theoretical or academic in the context of medieval life. If a mans neighbors in his community were selfish and malicious, the day-to-day consequences of that fact might be very distressing to him; on the other hand, if he acted out of malice himself, the result would be an uncomfortable isolation from the group that furnished his identity and made his own achievements meaningful.
Figure 1a The Church. Strassbourg Cathedral
The two laws or loves were not opposites; the New Law was thought of as a fulfillment of the Old, and charitable love was simply love directed toward" the invisible things of God" that lay beyond, but implicit in, the visible things of creation. When we see figures of the Church and the Synagogue on Gothic portals (Figure I ) ; we should recall that these figures do not represent a contrast between Christianity and Judaism literally; they exemplify, from a medieval point of view, determining factors in the behavior of any individual and in the structure of any community. The Synagogue stands with the broken staff of worldly dominion or tyranny in one hand and the tables of the Mosaic law drooping toward the earth in the other. Her blindfold indicates her inability to see spiritual realities beneath the surfaces of the visible and tangible. On the other side, the Church holds the Cross, the symbol of victory through penance, in one hand and the chalice of the grace of the New Law in the other. Among the throngs who enter the church between these two figures, there are those still bound in the spirit of the Synagogue by desire for self-satisfaction through things that may be seen or touched. Their hearts are set on wealth, power, fame, or the pleasures of the flesh. These are men who seek to dominate and exploit the communities to which they belong for their own selfish purposes, driven by that worst ingredient of what were called vices, or evil habits of the soul, malice. Beside them walk the more charitable, penitent for their transgressions, their hearts set on God, the supreme exemplar of justice, wisdom, and mercy. Perhaps sonic walked in one way on one day and in another on the next, but the charitable were those capable of the civilized restraints and daily sacrifices that make life in a community possible. At the same time, there was thought to be something of the Church and something of the Synagogue in every man. No one extricates himself completely from worldly concern, no matter how hard he may try to do so.
It should be emphasized that the attitudes of men of all kinds in this congregation are basically practical and not at all sentimental. It was felt that devotion to God was extremely reasonable and that those who pursued selfish ends were foolish and that their actions were self-defeating. The transitory world of the tangible was said to produce merely transient satisfactions leading to inevitable frustration. Creation was thought of as a grand hierarchy, but beyond the hierarchy of nature was a hierarchy of values that alone could satisfy a reasonable creature. The two statues thus stand as exemplifications of what we should call political, social, and psychological realities-realities that confront everyone daily in the ordinary conduct of life.
Until the last years of the Middle Ages men did not ordinarily think in what we would call political, social, and psychological terms. They easily identified their own interests with those of their communities, so that we should not be surprised to find, in medieval texts, problems of these three types all discussed in terms of morality. With reference to the last especially, it is significant that the word personality, used to mean the peculiar qualities of a given individual, did not come into current use until the eighteenth century, and that ideas like "the force of personality," or "the depths of personality," are peculiar to the nineteenth and twentieth centuries. Some recent theologians have, indeed, sought to locate God in the depths of the personality, and human personality has become a primary concern of modern literature and art. But such ideas, and the profound interest in psychology that accompanies them, are the products of an industrial civilization in which individuals find themselves more or less isolated in their efforts to achieve meaningful life as members of large, loosely formed groups. Medieval men were likely to think of their problems as community problems and of their own behavior in moral rather than in psychological terms. It is a mistake, therefore, to seek psychological profundity in medieval art or to expect characters in medieval literature to display personality in the modern sense of the word. There is no reason why this fact should be disappointing. The same shortcoming, if we wish to call it that, characterizes most classical literature and art as well. The better able we are to refrain from reading our own conventions into earlier literature and art, the better we shall be able to understand and, actually, to appreciate that literature and art and to understand the peculiar appeal of the literature and art of our own time.
During the Middle Ages human behavior was most often analyzed in terms of virtues and vices (Figure 2 ) . We have been taught by the nineteenth century to think of morality as being a dull subject, the concern of stuffy and hypocritical persons who are likely to seek to oppress our innocent natural inclinations so that we become even more unhappy than we already are. Concerning nineteenth-century morality all this may be true, for the Christianity of the period is characteristic
Figure 1b The Synagogue. Strassbourg Cathedral.
ally a religion of literal-minded righteousness rather than of love, frequently much closer in spirit to what medieval men called the Synagogue than to what they called the Church. Medieval morality was a different sort of thing entirely, embracing, as it did, much of the best ethical content of late classical thought. It was founded squarely on the principle that human behavior is ultimately a matter of love. The Christian conception of grace developed from the conviction that if men could be led to love properly, that is, to love intelligible
Figure 2 Tree of the Virtues ( 14C). The tree is here rooted in Humility, typified by the Blessed Virgin Mary at the Annunciation. Its fruits are the Cardinal Virtues numbered 1 through I V , each with seven attendant virtues, and the Theological Virtues, numbered V through Vll, each also with seven attendant virtues. The Figures at the bottom represent the Cardinal Virtues once more. From left to right they are Prudence, Justice, Fortitude, and Temperance.
rather than tangible realities, they could live together in harmony and be freed from the burdens of social oppression and personal frustration. Fluctuations between prosperity and adversity, or changes in Fortune, as they were called, would not affect them deeply. A virtuous man could, to paraphrase St. Augustine, love and do what he wished to do, satisfying his own desires and at the same time contributing to the welfare of his fellow men.
The vices that men were taught to avoid were described as essentially selfish habits of the soul springing from misdirected love. Such habits led to actions called sins, or actions contrary to reason. In accordance with the most popular classification developed during the Middle Ages, especially relevant to confession and penance, there were said to be seven such vices: pride (or vainglory), covetousness (or avarice), wrath, envy, sloth, gluttony, and lechery. The first five of these were usually thought of as being spiritual, and the last two as being physical, although the fifth, sloth, might have both physical and spiritual manifestations. Since the physical vices could manifest themselves without any very great element of malice, they were somewhat less serious than the first five. A man habitually inclined toward any one of them was said to be "vicious," his actions in manifesting them were called "sins," or, if they were especially grave, "crimes."Sins were said to be of two kinds: "venial" and "mortal."Venial sins, inadvertent rather than deliberate manifestations of the vices, were thought to be characteristic of ordinary human behavior. A sincere daily recitation of the Paternoster was considered a sufficient remedy for them, and no one was required to mention them at confession. But deliberate manifestations of the vices involving the full consent of the reason were "deadly" sins. Under the Old Law they incurred almost automatic damnation, but under the New Law the stains they left on the soul could be at least partially removed through contrition of heart, confession to a priest, and satisfaction, or the performance of acts of charity and self-denial.
From a practical point of view, a vicious person in these terms would be a disruptive element in his community, and the more elevated his station in the community hierarchy, the more dangerous his actions would become to its welfare. At the same time, it is not difficult to see that any of the vices might lead to what we would call alienation and frustration. Medieval men expressed a similar idea by saying that the vicious man was a slave to his own desires. The problem of sin was thus a very practical matter in daily life and not simply a manifestation of what is sometimes mistakenly assumed to be a characteristic medieval concentration on the afterlife.
The virtues commended by the medieval Church were subject to a variety of classifications, depending 011 the context in which they were being discussed. A virtue, like a vice, was described as a habit of the soul having its origin in love. That is, love directed toward creatures for their own sakes, or cupidity, led to vices.
Love directed toward God, who was frequently described as the epitome of power, wisdom, and love, or toward the intelligible, led to virtue. Using a distinction found in Cicero, medieval writers insisted that a virtue has two parts: an "office," or form of behavior, and an "end," or goal toward which the virtuous action is directed. A kind of behavior usually considered to be virtuous but motivated by selfish interests had the office of a virtue, but not its end. Such action was said to represent "false virtue," or "vice masquerading as virtue." For example, chastity had long been considered a virtue under certain circumstances in antiquity, and it was still regarded as a virtue in the Middle Ages. But chastity for a selfish end, like worldly reputation, was actually the manifestation of a vice. St. Gregory, for example, called such chastity "fornication of the spirit."It is obvious that persons who, either because they arc misguided or because they are deliberately malicious, disguise their vices as virtues may be even more dangerous to their communities than overtly vicious persons. It was often said that when Antichrist came, he would come not as a pagan but as a hypocrite. Among the virtues most frequently mentioned are the "theological" virtues and the "cardinal" virtues. The theological virtues - faith, hope, and charity - are perhaps the most difficult to describe in modern terms.
Today we have a great deal of what might be called scientific faith. That is, the scientist who performs certain operations in his laboratory has faith that similar materials under similarly controlled conditions will always behave in the same way. Even when he confesses that the laws he discovers are merely descriptions based on arbitrary classifications, he maintains his faith in their validity. Laymen are readily led to place even greater confidence in them, since they may result in better communications systems, foods, medicines, weapons, and so on. Medieval men, frequently to the disgust of modern historians of science, placed far less faith in "knowledge by experiment upon things seen."Their technology, although it grew considerably during the later Middle Ages, was comparatively underdeveloped. However, we should remember that technology depends for its development on the general structure of society; it grows to meet needs largely created by itself. Medieval men were more concerned with the values used to make human relationships meaningful, and to them the first requisite of such meaningful relationships was faith, not in the validity of natural law, but in God.
God has meant a great many different things to different people in the course of history, and the general concept of God has undergone changes over the centuries concomitant with changes in society. Medieval men tended to think in terms of hierarchies, and to them God represented the apex in the hierarchy of being. God was not, strictly speaking, the apex of the hierarchy of physical being, but the apex of the hierarchy of intelligible being. During the seventeenth and eighteenth centuries these two hierarchies became confused, so that the intelligible became a kind of upper extension of the visible. Once placed there, it became more and more remote, since it was clearly not subject to the same sort of analysis as was the visible hierarchy. The romantics still looked for it in the visible world, seeking God in nature, or transformed it into a transcendent infinite. Today, it has become increasingly difficult to comprehend the idea of an external reality of the intelligible, so that we seek various kinds of subjective reality to replace it. But we shall have difficulty understanding medieval art and literature unless we can imagine that men once believed firmly in an external realm of the intelligible readily accessible to the reason. To medieval men, God was something that existed outside of the world of space and time, except, that is, in His Incarnation. However, He permeated the physical world, through which He might be understood partly as in a mirror. He was also the source of the virtues. To believe in God was, among other things, to believe in the reality and efficacy of virtue. Faith was conventionally described as "belief in things unseen," and those things unseen supplied the necessary motivation for the kind of conduct that was thought to make life on earth satisfying and bearable. It was often said that God is love, and love was, as q e have seen, the binding force of community life.
To the medieval mind, if a man had no faith, he could not be expected to be virtuous except when an appearance of virtue suited his selfish interests. A faithless man was therefore regarded as an untrustworthy man. In medieval society, at least in the northern parts of Europe, contracts between lord and vassal were verbal rather than written. Their terms depended upon remembered custom, and their efficacy was a function of the int6grity of the parties. In a feudal kingdom a bond of fidelity extended by degrees from the serf on the manor to the king, and the king, theoretically at least, owed fealty to God for his holdings. The faith a man owed his fellows was felt to be an aspect of his faith in God. Faith placed in a temporal object for its own sake-in a man, in a woman, or in wealth or position-was regarded as false faith, in the nature of things inevitably frustrating and disappointing. Men, women, possessions, and worldly acquisitions of all kinds are subject to the whims of Fortune. He who has faith in them subjects himself to those whims also. Hope, the second of the theological virtues, is first of all the hope that men of goodwill may have for an eternal reward. But hope is not always a virtue, and whether it is virtuous or not, it is a matter of daily concern. The covetous man hopes that new wealth may be his, the lecherous man hopes for the favors of many ladies, and so on. The virtuous man hopes for a certain inner peace that comes with spontaneously virtuous inclinations, for fortitude to bear his afflictions, and for the peace and goodwill of his fellow men. Hope for temporal satisfaction was thought of as false hope dependent on Fortune. This does not mean that men could not hope to improve their lot. So long as such hope was consistent with common profit rather than centered on immediate personal satisfactions, it was thought to be virtuous.
The last of the theological virtues, often called the greatest of them, was charity, or love. All men, it was said, love, for without love a man would die, since he would have no interest in preserving himself or in perpetuating his species. Love, that is, was regarded as the source of all human motivation. Theologians explained that before the Fall Adam and Eve loved as they should, without concupiscence. After the Fall, in which both reason and love were impaired, man acquired the concupiscence that had formerly been proper only to the beasts, for without it he would not have protected himself and would have had no inclination to perpetuate his species. Human beings are said to inherit this concupiscence, so that all who are born in the world naturally love first of all those things that can be seen and touched. Through grace, however, provided by the example and teachings of Christ and by the Holy Spirit (or that aspect of the Trinity whose function is love), men may be contented with a sufficiency appropriate to their station and may direct their love toward the intelligible. That is, charity, combined with a reason restored at least partially to its original condition, removed malice from the heart and allowed men to function pleasurably as useful members of their communities. The idea that man should love God and his neighbors for the sake of God had profound social and political as well as psychological implications.
The cardinal virtues, actually an inheritance from antiquity, were justice, prudence, temperance, and fortitude. Allied with them were a host of other virtues, some gleaned from classical and Patristic authorities, and some, like courtesy and chivalry, derived from peculiarly medieval social needs. A special set of virtues, seven in number, was associated with the Gifts of the Holy Spirit and together these virtues were regarded as remedies for the seven principal vices.1 Thus the gift of the fear of God is effective against pride and conducive to the virtue of humility. The gift of piety is effective against envy and produces the virtue of benignity or friendship. Similarly, through the gift of knowledge, temperance replaces wrath ; through the gift of fortitude, prowess replaces sloth ; through the gift of counsel, mercy replaces avarice; through the gift of understanding, sobriety replaces gluttony; and through the gift of wisdom, chastity replaces lechery. The vices here have somewhat different connotations from those with the same names in the ordinary lists made for confessional purposes. It is clear, for example, that lechery, which here requires the highest gift of wisdom for its eradication, is not simply a matter of casual physical lapses and that gluttony is something more than a peasants occasional drunkenness. The fear of God was, on scriptural authority, regarded as the "beginning of wisdom," and the various steps beginning with humility and ending in wisdom represent an upward progress. If we look at the list as a whole, it becomes clear that virtue not only involves some sort of self-denial; it also entails positive and forceful effort for the sake of others. No man was expected to be altogether virtuous, but all men were encouraged to love virtue, which was, as Cicero had long ago pointed out in his treatise on friendship, the only satisfying source of amicable human relationships. One was urged to love his fellow man, not because he was accidentally human, but because he was either virtuous or potentially virtuous. The saints, the philosophers of antiquity, and the heroes of both ancient and medieval times were revered for their virtues.
Without virtue, it was felt, the communities of medieval society would have become stale, dull, and conducive to perpetual fear and suspicion. Ruskin regarded sin as a terrible and perpetual burden, and Cardinal Newman did not wish to encumber liberal education with the burden of virtue. But to the medieval mind, sin ceased to become a necessary burden with the New Law, and although all men were thought to be sinners, most could find some virtues suited to their station that they could regard with genuine reverence and even enthusiasm.
Whatever we may think of the Church today, or of Christianity generally, we should be careful not to confuse modern conditions with medieval conditions. During the Middle Ages the Church was responsible for the establishment and maintenance of civilized life in Western Europe. The literary monuments of Latin antiquity are for the most part available to us today only by virtue of the fact that they were copied by medieval scribes, typically in monasteries. We may say that the Church controlled medieval education, but the only reason it did s o was that it established and maintained educational institutions. Until the late Middle Ages no one was especially anxious to relieve the Church of this responsibility, and very few thought that the Church was oppressive or blindly authoritarian in doctrine. Members of the ecclesiastical hierarchy were, like everyone else, human. Some of them were notorious sinners, and some were ignorant, selfish, and locally oppressive. Churchmen participated freely in the life of the times. A bishop might be a great feudal lord, an abbot might profit considerably in the wool trade, and high ecclesiastics frequently held major positions in royal governments. In country parishes, the parson or vicar shared in the agricultural pursuits of his community. In a given country the ecclesiastical hierarchy was affected by the general health of the realm. Thus during the last quarter of the fourteenth century in England, the decay of political institutions was accompanied by a decay in ecclesiastical institutions. In general, when reform movements arose, their aim was not the establishment of a new secular morality, but the restoration of what were regarded as good ancient and traditional customs, based on a thoroughly Christian ideology. We should bear in mind that the revolt against Christianity that permeated much nineteenth-century and early-twentieth-century thought was a revolt against Christianity as it was conceived at the time, not as it was conceived in earlier times. Medieval authors lacked the avid pursuit of the new and different and the general rebelliousness that characterize modern authors. Their interests were still, generally, centered on their communities rather than on personal feelings and private problems.
1 For an excellent account of these virtues and their significance, see Rosemond Tuve, Allegorical Imagery, Princeton University Press, Princeton, N.J., 1966, chap. 2.