Thus the founder of the earthly city was a fratricide. Overcome with envy, he slew his own brother, a citizen of the eternal city, and a sojourner on earth. So that we cannot be surprised that this first specimen, or, as the Greeks say, archetype of crime, should, long afterwards, find a corresponding crime at the foundation of that city which was destined to reign over so many nations, and be the head of this earthly city of which we speak. For of that city also, as one of their poets has mentioned, "the first walls were stained with a brother's blood,"136 or, as Roman history records, Remus was slain by his brother Romulus. And thus there is no difference between the foundation of this city and of the earthly city, unless it be that Romulus and Remus were both citizens of the earthly city. Both desired to have the glory of founding the Roman republic, but both could not have as much glory as if one only claimed it; for he who wished to have the glory of ruling would certainly rule less if his power were shared by a living consort. In order, therefore, that the whole glory might be enjoyed by one, his consort was removed; and by this crime the empire was made larger indeed, but inferior, while otherwise it would have been less, but better. Now these brothers, Cain and Abel, were not both animated by the same earthly desires, nor did the murderer envy the other because he feared that, by both ruling, his own dominion would be curtailed, – for Abel was not solicitous to rule in that city which his brother built, – he was moved by that diabolical, envious hatred with which the evil regard the good, for no other reason than because they are good while themselves are evil. For the possession of goodness is by no means diminished by being shared with a partner either permanent or temporarily assumed; on the contrary, the possession of goodness is increased in proportion to the concord and charity of each of those who share it. In short, he who is unwilling to share this possession cannot have it; and he who is most willing to admit others to a share of it will have the greatest abundance to himself. The quarrel, then, between Romulus and Remus shows how the earthly city is divided against itself; that which fell out between Cain and Abel illustrated the hatred that subsists between the two cities, that of God and that of men. The wicked war with the wicked; the good also war with the wicked. But with the good, good men, or at least perfectly good men, cannot war; though, while only going on towards perfection, they war to this extent, that every good man resists others in those points in which he resists himself. And in each individual "the flesh lusteth against the spirit, and the spirit against the flesh."137 This spiritual lusting, therefore, can be at war with the carnal lust of another man; or carnal lust may be at war with the spiritual desires of another, in some such way as good and wicked men are at war; or, still more certainly, the carnal lusts of two men, good but not yet perfect, contend together, just as the wicked contend with the wicked, until the health of those who are under the treatment of grace attains final victory.
6. Of the weaknesses which even the citizens of the city of God suffer during this earthly pilgrimage in punishment of sin, and of which they are healed by God's care.
This sickliness – that is to say, that disobedience of which we spoke in the fourteenth book – is the punishment of the first disobedience. It is therefore not nature, but vice; and therefore it is said to the good who are growing in grace, and living in this pilgrimage by faith, "Bear ye one another's burdens, and so fulfil the law of Christ."138 In like manner it is said elsewhere, "Warn them that are unruly, comfort the feeble-minded, support the weak, be patient toward all men. See that none render evil for evil unto any man."139 And in another place, "If a man be overtaken in a fault, ye which are spiritual restore such an one in the spirit of meekness; considering thyself, lest thou also be tempted."140 And elsewhere, "Let not the sun go down upon your wrath."141 And in the Gospel, "If thy brother shall trespass against thee, go and tell him his fault between thee and him alone."142 So too of sins which may create scandal the apostle says, "Them that sin rebuke before all, that others also may fear."143 For this purpose, and that we may keep that peace without which no man can see the Lord,144 many precepts are given which carefully inculcate mutual forgiveness; among which we may number that terrible word in which the servant is ordered to pay his formerly remitted debt of ten thousand talents, because he did not remit to his fellow-servant his debt of two hundred pence. To which parable the Lord Jesus added the words, "So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother."145 It is thus the citizens of the city of God are healed while still they sojourn in this earth and sigh for the peace of their heavenly country. The Holy Spirit, too, works within, that the medicine externally applied may have some good result. Otherwise, even though God Himself make use of the creatures that are subject to Him, and in some human form address our human senses, whether we receive those impressions in sleep or in some external appearance, still, if He does not by His own inward grace sway and act upon the mind, no preaching of the truth is of any avail. But this God does, distinguishing between the vessels of wrath and the vessels of mercy, by His own very secret but very just providence. When He Himself aids the soul in His own hidden and wonderful ways, and the sin which dwells in our members, and is, as the apostle teaches, rather the punishment of sin, does not reign in our mortal body to obey the lusts of it, and when we no longer yield our members as instruments of unrighteousness,146 then the soul is converted from its own evil and selfish desires, and, God possessing it, it possesses itself in peace even in this life, and afterwards, with perfected health and endowed with immortality, will reign without sin in peace everlasting.
But though God made use of this very mode of address which we have been endeavouring to explain, and spoke to Cain in that form by which He was wont to accommodate Himself to our first parents and converse with them as a companion, what good influence had it on Cain? Did he not fulfil his wicked intention of killing his brother even after he was warned by God's voice? For when God had made a distinction between their sacrifices, neglecting Cain's, regarding Abel's, which was doubtless intimated by some visible sign to that effect; and when God had done so because the works of the one were evil but those of his brother good, Cain was very wroth, and his countenance fell. For thus it is written: "And the Lord said unto Cain, Why art thou wroth, and why is thy countenance fallen? If thou offerest rightly,