PREREQUISITES

The Physics Department at Cornell offers two intermediate-level undergraduate mechanics courses. This book evolved from lecture notes used in the more advanced of the two courses. Most of the students who took this course were considering postgraduate study leading to future careers in physics or astronomy. With a few exceptions, they had previously taken an introductory honors course in mechanics at the level of Kleppner and Kolenkow. Many students also had an Advanced Placement physics course in high school. Since we can assume that a solid background in introductory college-level physics already exists, we have not included a systematic review of elementary mechanics in the book, other than the brief example at the beginning of Chapter 1.

Familiarity with a certain few basic mathematical concepts is essential. The student should understand Taylor series in more than one variable, partial derivatives, the chain rule, and elementary manipulations with complex variables. Some elementary knowledge of matrices and determinants is also needed. Almost all of the students who took the honors analytic mechanics course at Cornell have either completed, or were concurrently registered in, a mathematical physics course involving vector analysis, complex variable theory, and techniques for solving ordinary and partial differential equations. However, a thorough grounding in these subjects is not essential – in fact some of this material can be learned by taking a course based on this book.

Of the order of the discussion, which requires that we speak first of the eternal punishment of the lost in company with the devil, and then of the eternal blessedness of the saints

We come next to the nature of the punishment which is to be visited upon the devil and all who belong to him when the two cities – the City of God and the city of the devil – have reached their deserved ends through Jesus Christ our Lord, the Judge of the living and dead. I shall in this book discuss this question more diligently, as far as God's help enables me to do so.

I have adopted this order, and preferred to deal with the felicity of the saints later, because, though both the saved and the damned will then be united with their bodies, it seems more incredible that bodies will endure in everlasting torments than that they will remain without any pain in eternal blessedness. Thus, when I have demonstrated that such punishment ought not to be thought unbelievable, this will be of great help to me; for it will make it easier to believe in the immortality of the bodies of the saints, which are delivered from all pain.

Moreover, this order is not at variance with the divine writings. For, in such writings, the blessedness of the good is sometimes put first, as in the words, ‘They that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.’

Preface

It is clear, then, that felicity consists in the full attainment of all desirable things. It is not a goddess, however, but a gift of God. Therefore no god should be worshipped by men except one who is able to bestow felicity on them. Hence, if felicity itself were a goddess, we might fairly say that Felicity alone would be the proper object of worship. But only God can confer those blessings which can be received even by men who are not good, and who therefore do not have felicity. Now, therefore, let us consider why He willed that the Roman empire should be so great and so enduring. For we have already argued at length that the great number of false gods whom the Romans worshipped did not accomplish this, and we shall continue to say this wherever it seems appropriate to do so.

That the cause of the Roman empire, and of all kingdoms, is not mere chance; nor does it consist in the position of the stars

According to the judgment or opinion of some, things happen by ‘chance’ when they have no cause, or no cause arising from a rational order, and by ‘fate’ when they come about not by the will of God or men, but as a result of a necessary sequence. The cause of the greatness of the Roman empire is therefore neither chance nor fate; for it is beyond doubt that human kingdoms are established by divine providence.

Preface: The plan and argument of the work here undertaken

Most glorious is the City of God: whether in this passing age, where she dwells by faith as a pilgrim among the ungodly, or in the security of that eternal home which she now patiently awaits until ‘righteousness shall return unto judgment’, but which she will then possess perfectly, in final victory and perfect peace. In this work, O Marcellinus, most beloved son – due to you by my promise – I have undertaken to defend her against those who favour their own gods above her Founder. The work is great and arduous; but God is our helper.

I know, however, what efforts are needed to persuade the proud how great is that virtue of humility which, not by dint of any human loftiness, but by divine grace bestowed from on high, raises us above all the earthly pinnacles which sway in this inconstant age. For the King and Founder of this City of which we are resolved to speak has revealed a maxim of the divine law in the Scriptures of His people, where it is said, ‘God resisteth the proud but giveth grace unto the humble.’ But the swollen fancy of the proud-spirited envies even this utterance, which belongs to God, and loves to hear the following words spoken in its own praise: ‘To spare the humble and subdue the proud.’

Of the creation of angels and men

As I promised in the last book, this final book of the whole work will contain a discussion of the eternal blessedness of the City of God. This City is called ‘eternal’ not because its existence is extended through many ages but will nonetheless at some time come to an end, but in the sense intended in the Gospel, where it is written that ‘of His kingdom there shall be no end’. Nor will that City be like an evergreen tree, where the same greenness seems to persist because the appearance of dense growth is preserved by the emergence of fresh leaves in the place of those which wither and fall: it will not present a mere appearance of perpetuity by new members arising to succeed those who die. Rather, all the citizens of that city will be immortal; for men also will obtain that which the angels have never lost. This will be brought about by God, the most almighty Founder of that City. For He has promised it, and He cannot lie; and He has shown His good faith by doing many things that He has promised, and many, indeed, that He has not promised.

For He it was Who in the beginning made the world and filled it with all good things, both visible and intelligible. Among these things, He created nothing better than those spirits to whom He gave intelligence, making them capable of contemplating and apprehending Him.

Of the matters discussed in the first book

When I began to speak of the City of God, I thought it necessary first of all to answer its enemies, who pursue earthly joys and long only for fleeting things. They rail against the Christian religion, which is the one saving and true religion, for whatever sorrows they suffer in respect of these things. And they do this even though they suffer rather through the mercy of God in admonishing them than from His severity in punishing.

Among those enemies there are many ignorant men whose hatred of us is all the more grievously inflamed by the authority of the learned. For the former believe that the extraordinary events which have occurred in their own day did not occur at all in times gone by; and they are supported in this belief even by those who know it to be false, but who conceal their knowledge in order to seem to have just cause for murmuring against us. It was necessary, therefore, to demonstrate from the books in which their own authors have recorded and published the history of times gone by, that matters are far other than the ignorant suppose. At the same time, it was necessary to teach that the false gods whom once they worshipped openly, and still worship in secret, are most vile spirits and malignant and deceitful demons: so much so that they take delight in crimes which, whether real or fictitious, are nonetheless their own, and which they have desired to have celebrated for them at their own festivals.

Whether any families are to be found in the period after the Flood from Noah to Abraham whose members lived according to God

Was the progress of the Holy City continuous from the time of the Flood onwards, or was it so disrupted by ungodliness that, at times, not one man existed who was a worshipper of the one true God? It is difficult to find in Scripture any clear statement as to this question. But, from the time of Noah, who, with his wife and three sons and their wives, was found worthy to be saved in the Ark from the devastation of the Flood, we do not find, until the time of Abraham, anyone in the canonical books whose godliness is proclaimed by the divine eloquence. The exception to this is when Noah commended his sons Shem and Japheth in his prophetic blessing; for he knew and foresaw what was to happen far in the future. Hence it was also that he cursed his middle son – that is, the one younger than the first-born but older than the last – who had sinned against his father. Noah did not curse Ham in his own person, but in the person of his son, in these words: ‘Cursed be Canaan; a servant of servants shall he be unto his brethren.’ Now Canaan was the son of Ham, who did not cover his sleeping father, but, rather, drew attention to his nakedness.