A: The covenant being made with Adam, not only for himself, but for his posterity, all mankind descending from him, by ordinary generation, sinned in him, and fell with him in his first transgression.
'By one man sin entered into the world, and death by sin,' &c. Rom 5:12.
Adam being a representative person, while he stood, we stood; when he fell, we fell, We sinned in Adam; so it is in the text, In whom all have sinned.'
Adam was the head of mankind, and being guilty, we are guilty, as the children of a traitor have their blood stained. Omnes unus ille Adam fuerunt. All of us,' says Augustine, sinned in Adam, because we were part of Adam.'
If when Adam fell, all mankind fell with him; why, when one angel fell, did not all fall?
The case is not the same. The angels had no relation to one another. They are called morning-stars; the stars have no dependence one upon another; but it was otherwise with us, we were in Adam's loins; as a child is a branch of the parent, we were part of Adam; therefore when he sinned, we sinned.
How is Adam's sin made ours?
(1.) By imputation. The Pelagians of old held, that Adam's transgression is hurtful to posterity by imitation only, not by imputation. But the text, In whom all have sinned,' confutes that.
(2.) Adam's sin is ours by propagation. Not only is the guilt of Adam's sin imputed to us, but the depravity and corruption of his nature is transmitted to us, as poison is carried from the fountain to the cistern. This is that which we call original sin. In sin did my mother conceive me.' Psa 51:1. Adam's leprosy cleaves to us, as Naaman's leprosy did to Gehazi.2 Kings 5:57. This original concupiscence is called,
(1.) The old man.' Eph 4:42. It is said to be the old man, not that it is weak, as old men are, but for its long standing, and for its deformity. In old age the fair blossoms of beauty fall; so original sin is the old man, because it has withered our beauty, and made us deformed in God's eye.
(2.) Original concupiscence is called the law of sin. Rom 7:75 Original sin has vim coactivam, the power of a law which binds the subject to allegiance. Men must needs do what sin will have them, when they have both the love of sin to draw them, and the law of sin to force them.
I. In original sin there is something privative, and something positive.
 Something privative. Carentia Justitiae debitae [The lack of that righteousness which should be ours]. We have lost that excellent quintessential frame of soul which once we had. Sin has cut the lock of original purity, where our strength lay.
 Something positive. Original sin has contaminated and defiled our virgin nature. It was death among the Romans to poison the springs. Original sin has poisoned the spring of our nature, it has turned beauty into leprosy; it has turned the azure brightness of our souls into midnight darkness.
Original sin has become co-natural to us. A man by nature cannot but sin; though there were no devil to tempt, no bad examples to imitate, yet there is such an innate principle in him that he cannot forbear sinning.2 Pet 2:14. A peccato cessare nesciunt, who cannot cease to sin, as a horse that is lame cannot go without halting. In original sin there is,
(1.) An aversion from good. Man has a desire to be happy, yet opposes that which should promote his happiness. He has a disgust of holiness, he hates to be reformed. Since we fell from God, we have no mind to return to him.
(2.) A propensity to evil. If, as the Pelagians say, there is so much goodness in us since the fall, why is there not as much natural proneness to good as there is to evil? Our experience tells us, that the natural bias of the soul is to that which is bad. The very heathens by the light of nature saw this. Hierocles the philosopher said, it is grafted in us by nature to sin.' Men roll sin as honey under their tongue. They drink iniquity as water,' Job 15:16. Like a hydropsical person, that thirsts for drink, and is not satisfied; they have a kind of drought on them, they thirst for sin. Though they are tired out in committing sin, yet they sin. Eph 4:19. They weary themselves to commit iniquity'; as a man that follows his game while he is weary, yet delights in it, and cannot leave it off. Jer 9:9. Though God has set so many flaming swords in the way to stop men in their sin, yet they go on in it; which all shows what a strong appetite they have to the forbidden fruit.
II. That we may further see the nature of original sin, consider,
 The universality of it. It has, as poison, diffused itself into all the parts and powers of the soul. The whole head is sick, and the whole heart is faint.' Isa 1:1. Like a sick patient, that has no part sound, his liver is swelled, his feet are gangrened, his lungs are perished; such infected, gangrened souls have we, till Christ, who has made a medicine of his blood, cures us.
(1.) Original sin has depraved the intellectual part. As in the creation darkness was upon the face of the deep,' Gen 1:1, so it is with the understanding; darkness is upon the face of this deep. As there is salt in every drop of the sea, bitterness in every branch of wormwood, so there is sin in every faculty. The mind is darkened, we know little of God. Ever since Adam did eat of the tree of knowledge, and his eyes were opened, we lost our eye-sight. Besides ignorance in the mind, there is error and mistake; we do not judge rightly of things, we put bitter for sweet, and sweet for bitter. Isa 5:50. Besides this, there is much pride, superciliousness and prejudice, and many fleshly reasonings. How long shall thy vain thoughts lodge within thee?' Jer 4:14.
(2.) Original sin has defiled the heart. The heart is deadly wicked. Jer 17:7. It is a lesser hell. In the heart are legions of lusts, obdurateness, infidelity, hypocrisy, sinful estuations; it boils as the sea with passion and revenge. Madness is in their heart while they live.' Eccl 9:9. The heart is, Officina diaboli, the devil's shop or workhouse,' where all mischief is framed.
(3.) The will. Contumacy is the seat of rebellion. The sinner crosses God's will, to fulfil his own. We will burn incense to the queen of heaven.' Jer 44:17. There is a rooted enmity in the will against holiness; it is like an iron sinew, it refuses to bend to God. Where is then the freedom of the will, when it is so full not only of indisposition, but opposition to what is spiritual?
(4.) The affections. These, as the strings of a viol, are out of tune. They are the lesser wheels, which are strongly carried by the will, the masterwheel. Our affections are set on wrong objects. Our love is set on sin, our joy on the creature. Our affections are naturally as a sick man's appetite, who desires things which are noxious and hurtful to him; he calls for wine in a fever. So we have impure lustings instead of holy longings.
 The adhesion of original sin. It cleaves to us, as blackness to the skin of the Ethiopian, so that we cannot get rid of it. Paul shook off the viper on his hand, but we cannot shake off this inbred corruption. It may be compared to a wild fig-tree growing on a wall, the roots of which are pulled up, and yet there are some fibres of it in the joints of the stonework, which will not be eradicated, but will sprout forth till the wall be pulled in pieces. Original concupiscence comes not, as a lodger, for a night, but as an indweller. Sin which dwelleth in me.' Rom 7:17.
It is a malus genius, an evil spirit' that haunts us wheresoever we go. The Canaanite would dwell in that land.' Josh 17:12.
 Original sin retards and hinders us in the exercise of God's worship. Whence is all that dullness and deadness in religion? It is the fruit of original sin. This it is that rocks us asleep in duty. The good that I would, I do not.' Rom 7:19. Sin is compared to a weight. Heb 12:2. A man that has weights tied to his legs cannot run fast. It is like that fish Pliny speaks of, a sea lamprey, that cleaves to the keel of the ship, and hinders its progress when it is under sail.
 Original sin, though latent in the soul, and as a spring which runs under ground, often breaks forth unexpectedly. Christian, thou canst not believe that evil which is in thy heart, and which will break forth suddenly, if God should leave thee. Is thy servant a dog that he should do this great thing?' 2 Kings 8:13. Hazael could not believe he had such a root of bitterness in his heart, that he should rip up the women with child. Is thy servant a dog? Yes, and worse than a dog, when that original corruption within is stirred up. If one had come to Peter and said, Peter, within a few hours thou wilt deny Christ, he would have said, Is thy servant a dog?' But alas! Peter did not know his own heart, nor how far that corruption within would prevail upon him. The sea may be calm, and look clear; but when the wind blows how it rages and foams! so though now thy heart seems good, yet, when temptation blows, how may original sin discover itself, making thee foam with lust and passion. Who would have thought to have found adultery in David, and drunkenness in Noah, and cursing in Job? If God leave a man to himself, how suddenly and scandalously may original sin break forth in the holiest men on the earth!
 Original sin mixes and incorporates itself with our duties and graces. (1.) With our duties. As the hand which is paralytic or palsied cannot move without shaking, as wanting some inward strength; so we cannot do any holy action without sinning, as wanting a principle of original righteousness. As whatever the leper touched became unclean; such a leprosy is original sin; it defiles our prayers and tears. We cannot write without blotting. Though I do not say that the holy duties and good works of the regenerate are sins, for that were to reproach the Spirit of Christ, by which they are wrought; yet this I say, that the best works of the godly have sin cleaving to them. Christ's blood alone makes atonement for our holy things.
(2.) With our graces. There is some unbelief mixed with faith, lukewarmness with zeal, pride with humility. As bad lungs cause an asthma or shortness of breath, so original corruption has infected our hearts, so that our graces breathe very faintly.
 Original sin is a vigorous active principle within us. It does not lie still, but is ever exciting and stirring us up to evil; it is an inmate very unquiet. What I hate, that do I,' Rom 7:15. How came Paul to do so? Original sin irritated and stirred him up to it. Original sin is like quicksilver, always in motion. When we are asleep, sin is awake in the fancy. Original sin sets the head plotting evil, and the hands working it. It has in it principium motus, not quietis [a principle of restlessness, not of tranquillity]; it is like the pulse, ever beating.
 Original sin is the cause of all actual sin. It is fomes peccati [the kindlingwood of sin], it is the womb in which all actual sins are conceived. Hence come murders, adulteries, rapines. Though actual sins may be more scandalous, yet original sin is more heinous; the cause is more than the effect.
 It is not perfectly cured in this life. Though grace does subdue sin, yet it does not wholly remove it. Though we are like Christ, having the first fruits of the Spirit, yet we are unlike him, having the remainders of the flesh. There are two nations in the womb. Original sin is like that tree, in Dan 4:43, though the branches of it were hewn down, and the main body of it, yet the stumps and root of the tree were left. Though the Spirit be still weakening and hewing down sin in the godly, yet the stump of original sin is left. It is a sea that will not, in this life, be dried up.
But why does God leave original corruption in us after regeneration? He could free us from it if he pleased.
(1.) He does it to show the power of his grace in the weakest believer. Grace shall prevail against a torrent of corruption. Whence is this? The corruption is ours, but the grace is God's.
(2.) God leaves original corruption to make us long after heaven, where there shall be no sin to defile, no devil to tempt. When Elias was taken up to heaven his mantle dropped off; so, when the angels shall carry us up to heaven, this mantle of sin shall drop off. We shall never more complain of an aching head, or an unbelieving heart.
Use one: If original sin be propagated to us, and will be inherent in us while we live here, it confutes the Libertines and Quakers, who say they are without sin. They hold perfection; they show much pride and ignorance; but we see the seeds of original sin remain in the best. There is not a just man lives and sins not.' Eccl 7:70. And Paul complained of a body of death.' Rom 7:74. Though grace purifies nature, it does not perfect it.
But does not the apostle say of believers, that their old man is crucified;' Rom 6:6, and they are dead to sin?' Rom 6:61.
They are dead. (1.) Spiritually. They are dead as to the reatus, the guilt of it; and as to the regnum, the power of it; the love of sin is crucified.
(2.) They are dead to sin legally. As a man that is sentenced to death is dead in law, so they are legally dead to sin. There is a sentence of death gone out against sin. It shall die, and drop into the grave; but at the present, sin has its life lengthened out. Nothing but the death of the body can quite free us from the body of this death.
Use two: Let us lay to heart original sin, and be deeply humbled for it. It cleaves to us as a disease, it is an active principle in us, stirring us up to evil. Original sin is worse than all actual sin; the fountain is more than the stream. Some think, as long as they are civil, they are well enough; ay, but the nature is poisoned. A river may have fair streams, but vermin at the bottom. Thou carriest a hell about thee, thou canst do nothing but thou defilest it; thy heart, like muddy ground, defiles the purest water that runs through it. Nay, though thou art regenerate, there is much of the old man in the new man. Oh how should original sin humble us!
This is one reason God has left original sin in us, because he would have it as a thorn in our side to humble us. As the bishop of Alexandria, after the people had embraced Christianity, destroyed all their idols but one, that the sight of that idol might make them loathe themselves for their former idolatry; so God leaves original sin to pull down the plumes of pride. Under our silver wings of grace are black feet.
Use three: Let the sense of this make us daily look up to heaven for help. Beg Christ's blood to wash away the guilt of sin, and his Spirit to mortify the power of it; beg further degrees of grace; gratiam Christi eo olonoxiam ambiamus. Though grace cannot make sin not to be, yet it makes it not to reign; though grace cannot expel sin, it can repel it. And for our comfort, where grace makes a combat with sin, death shall make a conquest.
Use four: Let original sin make us walk with continual jealousy and watchfulness over our hearts. The sin of our nature is like a sleeping lion, the least thing that awakens it makes it rage. Though the sin of our nature seems quiet, and lies as fire hid under the embers, yet if it be a little stirred and blown up by a temptation, how quickly may it flame forth into scandalous evils! therefore we need always to walk watchfully. I say to you all, Watch.' Mark 13:37. A wandering heart needs a watchful eye.