Many shall be purified, and made white, and tried; but the wicked shall do wickedly: and none of the wicked shall understand; but the wise shall understand. Many shall be purified - During the interim, the great work of God's providence and grace shall be carried on in the salvation of men; who, in the midst of trials, temptations, and difficulties, shall be purified and made white - be fully saved from their sins.
None of the wicked shall understand - Because they are wicked, and will continue in their sins, the eyes of their understanding shall be closed, and their hearts hardened; so that they shall not see the light of the glorious Gospel.
But the wise - Those who open their hearts to God, that he may pour in his light, shall understand the things that make for their peace.