Chapter III.
The seat or subject of the law of sin, the heart — What meant thereby — Properties of the heart as possessed by sin, unsearchable, deceitful — Whence that deceit ariseth — Improvement of these considerations.
Having manifested indwelling sin, whereof we treat in the remainders of it in believers, to be a law, and evinced in general the power of it from thence, we shall now proceed to give particular instances of its efficacy and advantages from some things that generally relate unto it as such. And these are three:— First, Its seat and subject; Secondly, Its natural properties; and, Thirdly, Its operations and the manner thereof; — which principally we aim at and shall attend unto.
First, For the seat and subject of this law of sin, the Scripture everywhere assigns it to be the heart. There indwelling sin keeps its especial residence. It hath invaded and possessed the throne of God himself: Eccles. ix. 3, “Madness is in the heart of men while they live.” This is their madness, or the root of all that madness which appears in their lives. Matt. xv. 19, “Out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies,” etc. There are many outward temptations and provocations that befall men, which excite and stir them up unto these evils; but they do but as it were open the vessel, and let out what is laid up and stored in it. The root, rise, and stirring of all these things is in the heart. Temptations and occasions put nothing into a man, but only draw out what was in him before, Hence is that summary description to the whole work and effect of this law of sin, Gen. vi. 5, “Every imagination of the thoughts of man’s heart is only evil continually;” so also chap. viii. 21. The whole work of the law of sin, from its first rise, its first coining of actual sin, is here described. And its seat, its work-house, is said to be the heart; and so it is called by our Saviour “The evil treasure of the heart:” Luke vi. 45, “An evil man, out of the evil treasure of his heart, bringeth forth evil things.” This treasure is the prevailing principle of moral actions that is in men. So, in the beginning of the verse, our Saviour calls grace “The good treasure of the heart” of a good man, whence that which is good doth proceed. It is a principle constantly and abundantly inciting and stirring up unto, and consequently bringing forth, actions conformable and like unto it, of the same kind and nature with itself. And it is also called a treasure for its abundance. It will never be exhausted; it is not wasted by men’s spending on it; yea, the more lavish men are of this stock, the more they draw out of this treasure, the more it grows and abounds! As men do not spend their grace, but increase it, by its exercise, no more do they their indwelling sin. The more men exercise their grace in duties of obedience, the more it is strengthened and increased; and the more men exert and put forth the fruits of their lust, the more is that enraged and increased in them; — it feeds upon itself, swallows up its own poison, and grows thereby. The more men sin, the more are they inclined unto sin. It is from the deceitfulness of this law of sin, whereof we shall speak afterward at large, that men persuade themselves that by this or that particular sin they shall so satisfy their lusts as that they shall need to sin no more. Every sin increaseth the principle, and fortifieth the habit of sinning. It is an evil treasure, that increaseth by doing evil. And where doth this treasure lie? It is in the heart; there it is laid up, there it is kept in safety. All the men in the world, all the angels in heaven, cannot dispossess a man of this treasure, it is so safely stored in the heart.
The heart in the Scripture is variously used; sometimes for the mind and understanding, sometimes for the will, sometimes for the affections, sometimes for the conscience, sometimes for the whole soul. Generally, it denotes the whole soul of man and all the faculties of it, not absolutely, but as they are all one principle of moral operations, as they all concur in our doing good or evil. The mind, as it inquireth, discerneth, and judgeth what is to be done, what refused; the will, as it chooseth or refuseth and avoids; the affections, as they like or dislike, cleave to or have an aversation from, that which is proposed to them; the conscience, as it warns and determines, — are all together called the heart. And in this sense it is that we say the seat and subject of this law of sin is the heart of man. Only, we may add that the Scripture, speaking of the heart as the principle of men’s good or evil actions, doth usually insinuate together with it two things belonging unto the manner of their performance:—