In Isaiah 25:6, 48:10, Zechariah 13:9, Malachi 3:2, 3, this signifies the purification of goods and truths from evils and falsities. (Arcana Coelestia 9293)
In Isaiah 25:6, this also signifies the state of people who will acknowledge and worship the Lord -- a feast of fat things signifies both natural and spiritual good, with joy of heart, and lees well refined, signifies truths from that good, and the happiness of it. (Apocalypse Explained 1159[3])