2Co 3:13 And not as Moses, which put a vail over his face, that the children of Israel could not stedfastly look to the end of that which is abolished:
2Co 3:14 But their minds were blinded: for until this day remaineth the same vail untaken away in the reading of the old testament; which vail is done away in Christ.
2Co 3:15 But even unto this day, when Moses is read, the vail is upon their heart.
2Co 3:16 Nevertheless when it shall turn to the Lord, the vail shall be taken away.
2Co 3:17 Now the Lord is that Spirit: and where the Spirit of the Lord is, there is liberty.
2Co 3:18 But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, even as by the Spirit of the Lord.
As a final push to explain the gospel ministry to the Corinthians, Paul talks about the veil that Moses wore in order to protect the children of Israel from his face as he brought the words of God to them.
He says that the children have this same veil over their hearts even today. And in fact, this veil is over all the hearts of those that are lost, leaving them spiritually blind.
We look at this passage and reevaluate our own roles in the mission, looking at it as our job to bring and offer sight to those that are blind. To offer light to rescue those in darkness. Also, that our spending time with God, just like Moses, should change us.