Once you were all darkness; now, in the Lord, you are all daylight. You must live as men native to the light; 9 where the light has its effect, all is goodness, and holiness, and truth;10 your lives must be the manifestation of God’s will. 11 As for the thankless deeds men do in the dark, you must not take any part in them; rather, your conduct must be a rebuke to them; 12 their secret actions are too shameful even to bear speaking of. 13 It is the light that rebukes such things and shews them up for what they are; only light shews up. 14 That is the meaning of the words, Awake, thou that sleepest, and arise from the dead, and Christ shall give thee light.
 ‘Manifestation’; the sense of the word is ‘to prove by experiment’, usually in the sense of convincing oneself. The context here suggests that the proof is for the benefit of others, as in I Cor. 3.13.
 ‘Only light shews up’; the Latin takes the verb in the sense of ‘to be manifest’, but the Greek allows of rendering it ‘to make (other things) manifest’, which is here more suitable to the context. Throughout this passage, St Paul is explaining that the witness of a Christian life, enlightened by grace, rebukes the wickedness of the surrounding world as inevitably as light reveals darkness.
 These words do not appear in Scripture, and some have thought that St Paul is quoting from a very early baptismal hymn.
You were once darkness, but now you are light in the Lord. Live as children of light, for light produces every kind of goodness and righteousness and truth. Try to learn what is pleasing to the Lord. Take no part in the fruitless works of darkness; rather expose them, for it is shameful even to mention the things done by them in secret; but everything exposed by the light becomes visible, for everything that becomes visible is light. Therefore, it says: “Awake, O sleeper, and arise from the dead, and Christ will give you light.”