On Loving God, by St Bernard of Clairvaux ~ Chapter 13: Of the Law of Self-Will and Desire, of Slaves and Hirelings.

Furthermore, the slave and the hireling have a law, not from the Lord, but of their own contriving; the one does not love God, the other loves something else more than God. They have a law of their own, not of God, I say; yet it is subject to the law of the Lord. For though they can make laws for themselves, they cannot supplant the changeless order of the eternal law. Each man is a law unto himself, when he sets up his will against the universal law, perversely striving to rival his Creator, to be wholly independent, making his will his only law. What a heavy and burdensome yoke upon all the sons of Adam, bowing down our necks, so that our life draweth nigh unto hell. 'O wretched man that I am! Who shall deliver me from the body of this death?' (Rom. 7.24). I am weighed down, I am almost overwhelmed, so that 'If the Lord had not helped me, it had not failed but my soul had been put to silence' (Ps. 94.17). Job was groaning under this load when he lamented: 'Why hast Thou set me as a mark against Thee, so that I am a burden to myself?' (Job 7.20). He was a burden to himself through the law which was of his own devising: yet he could not escape God's law, for he was set as a mark against God. The eternal law of righteousness ordains that he who will not submit to God's sweet rule shall suffer the bitter tyranny of self: but he who wears the easy yoke and light burden of love (Matt. 11.30) will escape the intolerable weight of his own self-will. Wondrously and justly does that eternal law retain rebels in subjection, so that they are unable to escape. They are subject to God's power, yet deprived of happiness with Him, unable to dwell with God in light and rest and glory everlasting. O Lord my God, 'why dost Thou not pardon my transgression and take away mine iniquity?' (Job 7.21). Then freed from the weight of my own will, I can breathe easily under the light burden of love. I shall not be coerced by fear, nor allured by mercenary desires; for I shall be led by the Spirit of God, that free Spirit whereby Thy sons are led, which beareth witness with my spirit that I am among the children of God (Rom. 8.16). So shall I be under that law which is Thine; and as Thou art, so shall I be in the world. Whosoever do what the apostle bids, 'Owe no man anything, but to love one another' (Rom. 13.8), are doubtless even in this life conformed to God's likeness: they are neither slaves nor hirelings but sons.