Where Christ as prophet teaches by his Spirit, he likewise as a king subdues the heart by his Spirit to obedience to what is taught. This is that teaching which is promised of God, when not only the brain but the heart itself is taught; when men do not only know what they should do but are taught the very doing of it. They are not only taught that they should love, fear and obey, but they are taught love itself, and fear and obedience themselves. Christ sets up his throne in the very heart and alters its direction, so making his subjects good, together with teaching them to be good. Other princes can make good laws, but they cannot write them in their people’s hearts (Jeremiah 31:33). This is Christ’s prerogative: he infuses into his subjects his own Spirit. . . The heart of a Christian is like Jerusalem when it was at its best, a city compact within itself (Psalm 122:3), where are set up thrones of judgment (Psalm 122:5). Judgment should have a throne in the heart of every Christian. Not that judgment alone will work a change. There must be grace to alter the bent and sway of the will before it will yield to be wrought upon by the understanding. But God has so joined these together that whenever he savingly shines on the understanding he gives a soft and pliable heart. For without a work upon the heart by the Spirit of God it will follow its own inclination to that which it loves, whatever the judgment shall say to the contrary. There is no natural proportion between an unsanctified heart and a sanctified judgment. For the unaltered heart will not give leave to the judgment coldly and soberly to conclude what is best, as a sick man, whilst his feverish illness corrupts his taste, is rather desirous to please that than to hearken to what the physician may say. Judgment has no power over itself where the will is unsubdued, for the will and affections bribe it to give sentence for them, when any profit or pleasure shall come in competition with that which the judgment only shall in general think to be good. And there it is, for the most part, in the power of the heart what the understanding shall judge and determine in particular things. Where grace has subdued the heart, unruly passions do not cast such a mist before the understanding that it does not see in particular cases what is best. Base considerations, springing from self-love, do not alter the case and bias the judgment into a contrary way; but that which is good in itself shall be good to us, although it crosses our particular worldly interests.    

The Bruised Reed - Richard Sibbes