John Chrysostom

A thick mist, a darkness and cloud is spread over all the earth. And, showing this, the Apostle said, "For we were once darkness." (Eph. v. 8) And again, "Ye, brethren, are not in darkness, that that day should overtake you as a thief." Since therefore there is, so to speak, a moonless night, and we walk in that night, God hath given us a bright lamp, having kindled in our souls the grace of the Holy Spirit. But some who have received this light have rendered it more bright and shining, as, for instance, Paul and Peter, and all those Saints; while others have even extinguished it, as the five virgins, as those who have "made shipwreck concerning the faith," as the fornicator of Corinth, as the Galatians who were perverted.

On this account Paul says, "Quench not the Spirit," that is, the gift of grace, for it is his custom so to call the gift of the Spirit. But this an impure life extinguishes. For as any one, who has sprinkled both water and dust upon the light of our lamp, extinguishes it, and if he does not this, but only takes out the oil-so it is also with the gift of grace. For if you have cast over it earthly things, and the cares of fluctuating matters, you have quenched the Spirit. And if you have done none of these things, but a temptation coming from some other quarter has vehemently assailed it, as some wind, and if the light be not strong, and it has not much oil, or you have not closed the opening, or have not shut the door, all is undone.