From a Cabinet of Jewels:

And there are the more inward and spiritual duties of religion, as the exercise of faith, fear, love, hope, joy, patience, contentation, humble submission, and choosing of God, and cleaving to God, and delighting in God, and admiring of God, and exalting of God, and following hard after God, and holy meditation, and self-examination, &c. Now all these lie in the very spirit of the command. Now in the exercise of these more spiritual duties our fellowship and communion with God mainly lies. In the more general duties of religion, an hypocrite may manifest the excellency of his gifts; but in the more spiritual duties of religion, a sincere Christian doth manifest both the excellency and efficacy of grace. Mark, an unsound heart looks no further than to the bare letter of the command, to bare hearing, and bare praying, and bare preaching, and bare fasting, and bare giving, and bare receiving, and bare suffering; he looks no further than to that part of the command which only binds the flesh, or outward man; and if he does but observe that in the gross, he thinks he hath done marvellous well; like a melancholy man, that matters not what melody and harmony he makes, so he does but touch the strings of the instrument. But now, a sound, a sincere Christian, he looks to the spirit of the command; and if he does not come up to that in sincere desires, in gracious purposes, in fixed resolutions, and in cordial endeavours, he can have no peace, no rest, no quiet, no comfort. O sirs! as ever you would see God, and enjoy God another day, you must labour, not only to obey the letter of the command, but also to bring your hearts to the sincere obedience of the spirit of the command. This is a very close, piercing, distinguishing, and discovering sign.

Thomas Brooks, The Complete Works of Thomas Brooks, ed. Alexander Balloch Grosart, vol. 3 (Edinburgh; London; Dublin: James Nichol; James Nisbet and Co.; G. Herbert, 1866), 340.