"That obedience that springs from faith is the obedience of a son, not of a slave;it is a free, voluntary, obedience, and not a legal, servile, and forced obedience: Ps. 106:3, 'Thy people shall be willing in the day of thy power, in the beauties of holiness;' Also in Ps. 27:8, 'When thou saidst, Seek ye my face, my heart said unto thee, Thy face, Lord, will I seek.' Now, no sooner had God given forth a word of command for the psalmist to seek him, and to seek his favor, but presently his heart did echo to that command: 'Thy face, Lord, will I seek.' Every gracious soul hath the duplicate of God's law in his heart, and is willingly cast into the mould of his word: Romans 6:17, 'Ye have obeyed from the heart the form of doctrine that hath been delivered to you'. They did not only obey, but they obeyed from the heart, their hearts were in their obedience: Ps. 40:8, 'I delight to do thy will, O my God! yea, thy law is within my heart,' these note the tenderest of affections. Oh! but now a true child of God, he has the law of God written, not only in his understanding, but also in his heart and affections, Ezek.36:25-27; and this is that which makes his obedience to be pleasing and delightful to him; so that if he might be free from the injunctions and directions of the word, like with the servant in the law, he would not value such a liberty, Exod. 21:4-6.
There is a principle within him agreeable to the precept without him, which makes all religious performances to be easy and pleasurable to him. Look, as the eye delights in seeing, and the ear in hearing, so a gracious heart (except when it is under a cloud of desertion, or in the school of temptation, or under some grievous tormenting afflictions, or sadly worsted by some prevalent corruption) delights in obeying. Actions of nature, you know, are actions of delight; and so are all those actions that spring from a new nature, a divine nature."
One thing I like about the Puritan writings is they are so practical; note how as he reveals the heart of devotion, he does not fail to include the realities of seasons of distress, temptation, afflictions, etc. I have found this to be lacking in the pulpits where I have attended. The lack of it can make those in the midst of a season of discouragement feel even worse.
Thomas Brooks - Photo of willing service by Gaby Gobou.