Evolution

On history, the truth, and the Catholic Church:
"An historian ought to regard everything as secondary in importance to truth, and moreover, the purity of the doctrine of the Catholic Church is evidenced by the fact of its being the most powerful, for often has it been tested by the attacks of opinionists of antagonistic dogmas. Yet, the disposal of the lot being of God, the Catholic Church has maintained its own ascendancy, has re-assumed its own power, and has led all the churches and the people to the reception of its own truth." [Book I, Chapter I]

On Constantine the Great granting equal rights to the celibate:
"There was an ancient Roman law, by which those who were unmarried at the age of twenty-five were not admitted to the same privileges as the married....The emperor, perceiving that this enactment militated against the interests of those who continued in a state of celibacy and remained childless for the sake of God, and deeming it absurd to attempt the multiplication of the human species by the care and zeal of man—nature always receiving increase or decrease according to the fiat from on high—made a law enjoining that the unmarried and childless should have the same advantages as the married." [Book I, Chapter IX]

On monks and the monastic life:
"Those who at this period had embraced monasticism, manifested the glory of the Church and evidenced the truth of their doctrines by their virtuous line of conduct. Indeed, the most useful thing that has been received by man from God is their philosophy." [Book I, Chapter XII]

"They practiced virtue, not only in word but in deed, and sought not honor of man. They manfully subjugated the passions of the soul, yielding neither to the necessities of nature, nor to the weakness of the body." [Book I, Chapter XII]

"They admired the beauty and simplicity of nature, but their hope was placed in heaven and the blessedness of the future." [Book I, Chapter XII]

"As they were diligent in all things and zealous in seeking the supreme good, their instructions, though clothed in modesty and prudence and devoid of vain and meretricious eloquence, possessed power, like sovereign medicines, in healing the moral diseases of their audience. They spoke, too, with fear and reverence, and eschewed all strife, raillery, and anger." [Book I, Chapter XII]

Constantine the Great responds to priests bringing accusations against each other:
"'All these accusations will be brought forward at the great day of judgment, and will be judged by the Great Judge of all men. As to me, I am but a man, and it would be evil in me to take cognizance of such matters, seeing that the accuser and the accused are priests, and priests ought so to act as never to become amenable to the judgment of others. Imitate, therefore, the divine love and mercy of God, and be ye reconciled to one another. Withdraw your accusations against each other, be ye of one mind, and devote your attention to those subjects connected with the faith on account of which we are assembled.' After having thus urged them to cease from criminating each other, the emperor commanded the memorials to be burnt." [Book I, Chapter XVII]

Constantine the Great on dissension in the Church:
"'It is my desire that you should be of one mind and hold the same opinions in fellowship of spirit, for dissension in the Church of God is the greatest of evils.'" [Book I, Chapter XIX]

Constantine the Great in response to Acesius, a Novatian heretic who believed that certain sins could not be forgiven:
“O Acesius, take a ladder and ascend alone to heaven.” [Book I, Chapter XXII]

How Saint Helena, Constantine's mother, discovered the True Cross:
"There was a certain lady of rank in Jerusalem who was afflicted with a grievous and incurable disease. Macarius, bishop of Jerusalem, accompanied by the mother of the emperor and her attendants, repaired to her bed-side. After engaging in prayer, Macarius signified by signs to the spectators that the divine cross would be the one which, on being brought in contact with the invalid, should remove the disease. He approached her in turn with each of the crosses, but when two of the crosses were laid on her, it seemed but vanity and mockery to her, for she was at the gates of death. When, however, the third cross was in like manner brought to her, she immediately opened her eyes, regained her strength, and arose. It is said that a dead person was, in the same way, restored to life." [Book II, Chapter I]

On why the pagans converted to Christianity under Constantine:
"The efforts of the emperor succeeded to the utmost of his anticipations for, on beholding the objects of their former reverence and fear boldly cast down and stuffed with straw and hay, the people were led to despise what they had previously venerated, and to blame the erroneous opinion of their ancestors. Others, envious at the honor in which Christians were held by the emperor, deemed it necessary to conform to the imperial institutions. Others devoted themselves to an examination of Christianity, and by means of signs, of dreams, or of conferences with monks and bishops, were led to a conviction of its truth." [Book II, Chapter V]

On the number of Christians martyred in Persia under Sapor:
"The number of men and women whose names have been ascertained, and who were martyred at this period, has been computed to be upwards of sixteen thousand, while the multitude of martyrs whose names are unknown was so great that the Persians, the Syrians, and the inhabitants of Edessa, have failed in all their efforts to compute the number." [Book II, Chapter XIV]

Sozomen's opinion of Saint Athanasius the Great of Alexandria:
"I am convinced that it was by Divine appointment that Athanasius succeeded to the bishopric, for he was eloquent and intelligent, and capable of opposing the machinations of his enemies and, in fact, well suited to the times in which he lived. He displayed great aptitude in the exercise of the ecclesiastical functions, and in the instruction of the people and was, so to speak, self-taught in these respects." [Book II, Chapter XVII]

How Arius the heresiarch died:
"On the evening of the same day, Arius, being seized with pain in the stomach, was compelled to repair to the public place set apart for emergencies of this nature. As some time passed away without his coming out, some persons who were waiting for him outside entered and found him dead and still sitting upon the seat....It is said that for a long period subsequently, no one would make use of the seat on which he died. Those who were compelled by necessities of nature to visit the public place, always avoided with horror the precise spot on which the impiety of Arius had been visited with judgment. At a later epoch a certain rich and powerful man, who had embraced the Arian tenets, bought the place of the public, and built a house on the spot, in order that the occurrence might fall into oblivion, and that there might be no perpetual memorial of the death of Arius." [Book II, Chapter XXIX and XXX]

On the death of Constantine the Great:
"He died in the sixty-fifth year of his age, and the thirty-first of his reign. He was a powerful protector of the Christian religion, and was the first of the emperors who manifested zeal in the extension of the church. He was more successful than any other sovereign in all his undertakings, for he formed no design, I am convinced, without God. He was victorious in his wars against the Goths and Sarmatians and, indeed, in all his military enterprises, and he changed the form of government according to his own mind with so much ease that he created another senate and another capital city to which he gave his own name. He utterly subverted the Grecian religion, which had prevailed for ages among the princes and the people." [Book II, Chapter XXXIV]

Saint Anthony the Great's advice to Didymus the Blind:
"It is related that when Antony left the desert and repaired to Alexandria to give his testimony in favor of the doctrines of Athanasius, he said to Didymus, 'It is not a great misfortune, O Didymus, to be deprived of the organs of sight which are possessed by rats, mice, and the lowest animals, but it is a great blessing to possess eyes like angels, whereby you can contemplate the Divine Being and attain to true knowledge.'" [Book III, Chapter XV]

On the progress of the Christian religion under the sons of Constantine:
"Those who presided over the churches at this period were noted for purity of life and, as might be expected, the people whom they governed were earnestly attached to the service of Christ. Religion daily progressed and the zeal, virtue, and wonderful works of the priests and of the ecclesiastical philosophers attracted the attention of the Greeks and led them to renounce their superstitions. The emperors who then occupied the throne were as zealous as was their father in protecting the churches, and they granted honors and privileges to the clergy, their children, and their slaves. They confirmed the laws enacted by their father and enforced new ones, prohibiting the offering of sacrifice and the observance of other Pagan ceremonies. They commanded that all temples, whether in cities or in the country, should be closed." [Book III, Chapter XVII]

How the appearance of a cross in the heavens caused many to convert to Christianity:
"At the time that Cyril succeeded Maximus in the government of the church of Jerusalem, the sign of the cross appeared in the heavens. Its radiance was not feeble and divergent like that of comets, but splendid and concentrated. Its length was about fifteen stadia from Calvary to the Mount of Olives, and its breadth was in proportion to its length. So extraordinary a phenomenon excited universal terror. Men, women, and children left their houses, the marketplace, or their respective employments, and ran to the church, where they sang hymns to Christ together, and voluntarily confessed their belief in God....It was said that this prodigy was the fulfillment of an ancient prophecy contained in the Holy Scriptures. It was the means of the conversion of many Greeks and Jews to Christianity." [Book IV, Chapter VI]

The response of Pope Liberius to the emperor Constantius II upon being banished:
"It is said that when he was being conducted to banishment, the emperor sent him five hundred pieces of gold. He, however, refused to receive them and said to the messenger who brought them, 'Go, and tell him who sent this gold, to give it to the flatterers and hypocrites who surround him, for their insatiable cupidity plunges them into a state of perpetual want which can never be relieved. Christ, who is, in all respects, like unto his Father, supplies us with food and with all good things.'" [Book IV, Chapter XI]

On the Roman See being occupied by two bishops at once:
"Felix survived but a short time, and Liberius found himself in sole possession of the church. This event was, no doubt, ordained by God that the seat of Peter might not be dishonored by the occupancy of two bishops, for such an arrangement, being contrary to ecclesiastical law, would certainly have been a source of discord." [Book IV, Chapter XV]

On innovation and tradition in the Church:
"When the spirit of innovation becomes regarded with popular favor, it is scarcely possible to arrest its progress. Inflated as it always is with arrogance, it contemns the institutions of the Fathers, and enacts laws of its own. It even despises the theological doctrines of antiquity, and seeks out zealously a new form of religion of its own devising." [Book IV, Chapter XXVII]

How the family of Sozomen converted to Christianity:
"My grandfather was of Pagan parentage, and with his own family and that of Alaphion, had been the first to embrace Christianity in Bethelia, a populous town near Gaza, in which there are temples highly reverenced by the people of the country on account of their extreme antiquity....It is said that the above-mentioned families were converted through the instrumentality of the monk Hilarion. Alaphion, it appears, was possessed of a devil, and neither the Pagans nor the Jews could by any of their enchantments deliver him from this affliction. But Hilarion, by simply calling upon the name of Christ, expelled the demon, and Alaphion with his whole family immediately embraced the faith." [Book V, Chapter XV]

How the bishops responded to the condemnation of Julian the Apostate:
"The emperor, for the purpose of casting ridicule on works of this nature [Christian apologias], wrote to the bishops in the following words: 'I have read, I have understood, and I have condemned.' To this they sent the following reply: 'You have read, but you have not understood, for had you understood, you would not have condemned.'" [Book V, Chapter XVIII]

On Julian's attempt to rebuild the Temple in Jerusalem:
"The emperor, the other Pagans, and all the Jews, regarded every other undertaking as secondary in importance to this. Although the Pagans were not well-disposed towards the Jews, yet they assisted them in this enterprise because they reckoned upon its ultimate success and hoped by this means to falsify the prophecies of Christ. Besides this motive, the Jews themselves were impelled by the consideration that the time had arrived for rebuilding their temple. When they had removed the ruins of the former building and had cleared the ground for the purpose of laying the foundations of the new edifice, an earthquake occurred and stones were thrown up from the earth, by which those who were engaged in the work were wounded, as likewise those who were merely looking on. The houses and public porticoes near the site of the temple were thrown down. Many people lost their lives and others were horribly mutilated." [Book V, Chapter XXII]

On whether Julian had a vision of Christ at his death:
"I know not whether on the approach of death and while his soul was in the act of being separated from the body, he might have become invested with superhuman powers and so have beheld Christ. Few allusions have been made to this subject, and yet I dare not reject this hypothesis as absolutely false, for God often suffers still more improbable and astonishing events to take place in order to prove that the Christian religion rests not on the wisdom or the power of man." [Book VI, Chapter II]

How the emperor Valentinian I responded to the demands of his soldiers:
"'It depended on you alone, O soldiers, to proclaim me emperor. But now that you have elected me, it depends not upon you but upon me to perform what you demand. Remain quiet, as subjects ought to do, and leave me to act as an emperor.'" [Book VI, Chapter VI]

The ill effects of private quarrels among the clergy:
"The private animosities of the clergy tend to the injury of the church, and the introduction of many heresies in religion." [Book VI, Chapter XXV]

How disputes over dogma retard the spread of the Gospel:
"These varying dogmas are the sources of innumerable troubles, and many are deterred from embracing Christianity by the diversity of opinion which prevails in matters of doctrine." [Book VI, Chapter XXVI]

On the amazing conversion of Saint Moses the Black:
"Moses was originally a slave but was driven from his master’s house on account of his perversity. He joined some robbers and became leader of the band. After having perpetrated several murders and other crimes, he embraced a life of asceticism and attained the highest point of philosophical perfection....So sudden a conversion from vice to virtue was never before witnessed, nor such rapid attainments in monastical philosophy. Hence God rendered him an object of dread to the demons and he was ordained presbyter over the monks at Scetis." [Book VI, Chapter XXIX]

How Isaac the monk predicted the death of the emperor Valens:
"When Valens was on the point of departing from Constantinople, Isaac, a monk of great virtue who feared no danger in the cause of God, presented himself before him and addressed him in the following words: 'Give back, O emperor, to the orthodox and to those who maintain the Nicene doctrines, the churches of which you have deprived them and the victory will be yours.' The emperor was offended at this act of boldness and commanded that Isaac should be arrested and kept in chains until his return when he meant to bring him to justice for his temerity. Isaac, however, replied, 'You will not return unless you restore the churches.' And so, in fact, it came to pass. [Book VI, Chapter XL]

On the ancient sacrament of Penance in the Roman Church:
"As the custom of doing penance never gained ground among the Novatians, regulations of this nature were, of course, unnecessary among them, but the custom prevailed among all other religious sects and exists even to the present day. It is observed with great rigor by the Western churches, particularly at Rome where there is a place appropriated to the reception of penitents, where they stand and mourn until the completion of the solemn services, from which they are excluded, then they cast themselves with groans and lamentations prostrate on the ground. The bishop conducts the ceremony, sheds tears, and prostrates himself in like manner, and all the people burst into tears and groan aloud. Afterwards, the bishop rises from the ground and raises up the others. He offers up prayer on behalf of the penitents and then dismisses them. Each of the penitents subjects himself in private to voluntary suffering, either by fastings, by abstaining from the bath or from divers kinds of meats, or by other prescribed means, until a certain period appointed by the bishop. When this time arrives, he is made free from the consequences of his sin and is permitted to resume his place in the assemblies of the church. The Roman priests have carefully observed this custom from the beginning to the present time." [Book VII, Chapter XVI]

How Saint Ambrose courageously confronted the emperor Theodosius the Great:
"After the death of Eugenius, the emperor went to Milan and repaired toward the church to pray within its walls. When he drew near the gates of the edifice, he was met by Ambrose, the bishop of the city, who took hold of him by his purple robe and said to him in the presence of the multitude, 'Stand back! A man defiled by sin and with hands imbrued in blood unjustly shed is not worthy, without repentance, to enter within these sacred precincts or partake of the holy mysteries.'" [Book VII, Chapter XXV]

On the virtues and eloquence of St. John Chrysostom:
"It was chiefly by the bright example of his private virtues that John inspired his auditors with emulation. He produced conviction the more readily because he did not resort to rhetorical artifices but expounded the Sacred Scriptures with truth and sincerity. Arguments which are corroborated by actions always commend themselves as worthy of belief, but when a preacher’s deeds will not bear investigation, his words, even when he is anxious to declare the truth, are regarded as contradictory. John taught both by precept and example, for while, on the one hand, his course of life was virtuous and austere, on the other hand, he possessed considerable eloquence and persuasiveness of diction. His natural abilities were excellent, and he improved them by studying under the best masters." [Book VIII, Chapter II]

How Saint John Chrysostom enraged the Empress Eudoxia:
"Not long after these occurrences, the silver statue of the empress which is still to be seen to the south of the church opposite the grand council-chamber, was placed upon a column of porphyry, and the event was celebrated by loud acclamations, dancing, games, and other manifestations of public rejoicing, usually observed on the erection of the statues of the emperors. In a public discourse to the people, John declared that these proceedings reflected dishonor on the church. This remark recalled former grievances to the recollection of the empress and irritated her so exceedingly that she determined to procure the convocation of another council. Instead of striving to conciliate her, John added fuel to her indignation by openly declaiming against her in the church, and it was at this period that he pronounced the memorable discourse commencing with the words, 'Herodias is again enraged. Again she dances. Again she demands the head of John in a basin.'" [Book VIII, Chapter XX]

On piety and imperial power:
"It appears to me that it was the design of God to show by the events of this period that piety alone suffices for the safety and prosperity of princes, and that without piety, armies, a powerful empire, and political resources are of no avail." [Book IX, Chapter I]

On the zeal and vigilance of the princess-regent, Pulcheria:
"Many troubles which would have been excited in the church at this period by the influence of erroneous opinions, were averted by her zeal and vigilance. It is mainly owing to her prudence, as we shall have occasion to show in the afterpart of this history, that we are at the present time preserved from new heresies." [Book IX, Chapter I]

On piety and imperial power, again:
"To insure the stability of imperial power, it is sufficient for an emperor to serve God with reverence." [Book IX, Chapter XVI]