When I was in the RCIA classes, they did a little demonstration on purgatory. What they did was they made the entire room dark, wait a few minuets for our eyes to adjust to the room, and then BOOM! The lights turned on (and you know how it feels to see light after being in the dark for so long.) Father told us that that is what Purgatory’s like. A transition between our sinful nature to a sinless body in the presence of our Lord.
That is what I was taught about purgatory.