How Sibbes develops the understanding of sin as a “wound and disease.” He begins with a partial observation on it is like to suffer a disease:
Now, as in sickness there is, 1, grief troubling and vexing the party who feels it; and, 2, deformity of the place affected, which comes by wounds and weaknesses;
This description is then applied from the metaphor to the original. If a disease in the body causes vexation and deformity, then so does sin. But sin, rather than troubling the body alone, troubles the mind and the body:
so in all sin, when we are sensible of it, there is first grief, vexation, and torment of conscience, and then, again, deformity. For it takes away the beauty and vigour of the soul, and dejects the countenance. It debaseth a man, and takes away his excellency.… So that sin is a wound and a disease, whether we consider the miseries it brings on soul and body, or both
It has always been the case that some sin or another is not a cause for shame in the culture but rather a boast. In some ages, extraordinary violence is a cause for praise; in others, greed; in others, lust. It is not just that such sins have always existed among us; it is that certain sins become a cause for praise. But to God, no amount of human praise will undo the deformity of sin:
Therefore, howsoever a sinful person think himself a goodly person, and wear his sins as ornaments about him, pride, lust, and the like, yet he is a deformed, loathsome person in the eyes and presence of God;
This judgment, “when the conscience is awakened” becomes our own evaluation of our own sin.
And when conscience is awakened, sin will be loathsome, irksome, and odious unto himself, fill him full of grief and shame, so that he cannot endure the sight of his own soul.
The language when “awakened” is important to understand. It is not bare conscience alone which is the judge of all things. On this point Bloesch writes:
The inner light or the light of conscience also reflects the indissoluble mystery of the divine in the human. Conscience is both the voice of Christ and the superego. Only a conscience that is captive to the Word of God (Luther) is absolutely normative for the Christian. Conscience is not so much a criterion as a clarification of the truth of faith (Ellul). Moreover, conscience can be lost with the demise of faith (1 Tim 1:19–20 NIV). Like the church it can be seared and maimed (1 Tim 4:2), but so long as the believer is linked with Christ in the mystery of faith, conscience will always be somewhat of a guide on the pilgrimage of faith.
The Enlightenment severed conscience from faith in the living God, elevating it to an independent criterion that actually opposed the claims of faith. This new understanding is to be found in Rousseau: “Conscience! Conscience! Divine instinct, immortal voice from heaven; sure guide for a creature ignorant and finite indeed, yet intelligent and free; infallible judge of good and evil, making man like to God!”40 It is also reflected in the idealist philosopher Fichte: “Conscience alone is the root of all truth: whatever is opposed to conscience, or stands in the way of the fulfillment of her behests, is assuredly false.”
Donald G. Bloesch, A Theology of Word & Spirit: Authority & Method in Theology (Downers Grove, IL: InterVarsity Press, 2005), 201.
Continuing with the metaphor of disease, Sibbes continues that our current disease of sin flows from the hereditary disease of Adam’s sin:
Now, all sins whatsoever are diseases. The first sin of all sins, which we call hereditary, original sin, what was it but an hereditary disease? Now, all other particular, actual sins be diseases flowing from hence.
What are the sources of our diseases: flesh (ourselves), the world (others), the devil.
So that all diseases in this kind arise either, 1, from ourselves, as we have a seminary of them in our own hearts; or else, 2, from the infection and contagion of others; or, 3, from Satan, who hath society with our spirits, as men have with the outward man, coming in by his suggestions, and our entertaining of them. So that in that respect sin is like unto a wound and a disease, in regard of the cause of them.
Having consider causes of this disease, he now turns to the effects of considered as a disease. A disease left unchecked will kill: “And, in regard of the effects, sin is like a disease. Diseases, if they be neglected, breed death itself, and become incurable. So it is with the diseases and sins of the soul. Neglect them, and the best end of them will be despair in this world.“
Sibbes does not wait unti the end of the sermon to make his application. The constant movement of his preaching is to make a point and then apply it. Sin is a disease which will kill us. He then immediately moves to the cure: “Whereupon we may have advantage to fly unto the mercy of God in Christ. This is the end of sin, either to end in a good despair or in a fruitless barren despair, at the hour of death leading to hell, when they have no grace to repent. ‘The wages of sin is death,’ &c., Rom. 6:23.“
In this section, Sibbes is seeking to obtain an emotional effect. He does this by using figures of expansion and repetition. Notice how often he repeats the words “disease” and “sin” and “wound”. Following that, he gives a series of six questions, all which use the form, “What is X … but”:
Sin itself is a wound, and that which riseth from sin is a wound too, doubting and despair; for this disease and wound of sin breeds that other disease, a despair of mercy, which is the beginning of hell, the second death. These things might be further enlarged. But for the present only in general know that sin is a disease and a wound of the soul; so much worse than the diseases of the body, by how much the soul is more precious than it, and the death of the soul more terrible than the death of the body.
Sin is a disease and a wound; for
what is pride but a swelling?
What is anger but an intemperate heat of the soul, like an ague, as it were?
What is revenge but a wildfire in the soul?
What is lust but a spreading canker in the soul, tending to a consumption?
What is covetousness but a sword, a perpetual wounder of the soul, piercing it through with many sorrows?
What is security but, as it were, the lethargy and apoplexy of the soul?
At this point, he anticipates a question:
Quest. But, it may be demanded, how shall we know that we are sick of this sickness and disease you speak of?
This is interesting: we can know our spiritual state from the nature of our affections or “passions” (emotions). The Puritans, and those who followed in their wake, had an intense concern with the nature of human emotion:
Ans. How do we know that we are sick in body? If the body be extreme cold we know there is a distemper, or if it be extreme hot. So if the soul be so extreme cold that no heavenly motives or sweet promises can work upon it, stir it up, then certainly there is a disease upon the soul.
If the soul be inflamed with revenge and anger, that soul is certainly diseased. The temper of the soul is according to the passions thereof. A man may know by his passions when he hath a sick soul.
He then develops this idea by means of the analogy. Look at the human body. A man must be very sick to be unaware of what is taking place in his body. The same with the soul: a must be very spiritually sick when he is unaware of what is taking place spiritually or morally. In particular, again, working through the analogy to the body, an inability to respond to the Word of God is evidence of sickness, “And there is certainly some sickness, some dangerous obstruction in that soul that cannot digest the wholesome word of God, to make use of it; some noisome lust then certainly obstructs the soul, which must be purged out.”
Now if this is sickness then the greatest sickness must be not merely an inability to use the Word of God, but even more refuse it:
It is a pitiful thing to see the desperate condition of many now, who, though they live under the tyranny of sin, yet flatter their own disease, and account them their greatest enemies who any way oppose their sick humour. What do they most cordially hate? The sound preaching of the word.
After having developed that theme at some length he comes to the end of such a state. The desire to live without limitation on my desires (and thus without the Word of God) is the worst of all possible states:
O that I might live as I list, that I might have what would content my pleasures without control, that I might have no crosses, but go smoothly on! Yet this, which is the desire of most men, is the most cursed estate of all, and most to be lamented. Thus it appeareth sin is a wound and a disease. What use may we make of it?
 Friend, if God hath thy negative obedience, some other hath thy positive,—for I cannot suppose thee idle all the time of thy life,—either the devil, or the world, or the flesh; man cannot live without a master, whose work and business he will do
George Swinnock, The Works of George Swinnock, M.A., vol. 5 (Edinburgh; London; Dublin: James Nichol; James Nisbet and Co.; G. Herbert, 1868), 397.