Look what that is to which the heart doth secretly render the glory of a duty, and that is the principle of the duty. In Hab. i, 16, we read of them that “sacrifice to their net, and burn incense to their drag.” Where the glory of an action is rendered to a man’s self, the principle is self. All rivers run into the sea; that is an argument that they come from the sea: so when all a man’s duties terminate in self, then is self the principle of all. Now all the natural man’s duties run into self. He was never by a thorough work of grace, truly cast out of himself; and brought to deny himself; and therefore he can rise no higher than himself in all he does.
He never was brought to be poor in spirit, and so to live upon another; to be carried out of all duties to Christ.
But the believer giveth the glory of all his services to God; whatever strength or life there is in duty, God hath all the glory, for he is by grace out of himself, and therefore seeth no excellence or worthiness in self.
“I labored more abundantly than they all,” saith the apostle; but to whom doth he ascribe the glory of this? to self? No! “Yet not I” saith he “but the grace of God which was with me.” Wherever the grace of Christ is wrought in the heart as a principle of duty, you shall find the soul when it is most carried out, with a “yet not I” in the mouth of it. “I live, yet not I.” “I labored more abundantly than all. Yet not I.” Self is disclaimed, and Christ most advanced, when it is from grace that the heart is quickened. The twenty-four elders “cast their crowns at Jesus’ feet.”