Time began when we, as a unified creation of God, decided (then forgot) to be the concept of a individual. We believed we broke apart from God and could think for ourselves, and think private, unshared thoughts. That we forgot about this decision was because of the fear we made at the same time.
An analogy could be that we were like a young child that broke a mirror and ran to hide in fear of our parents; except that we thought we broke our unity, and have been running ever since.
Perhaps the best (two-dimensional) description could be that we were a falling mirror or pane of glass, such that during the fall we reflected a distorted and disorienting view of the world. When we hit, we broke apart and spread out. Because of the ripple effect from the impact, some center pieces came to rest almost immediately, while the outer-edge pieces are still kinetically spreading apart. (I've always wondered if our constant population growth on Earth is really a sign of further fragmentation.)
C28:4:9:5: The forms the broken pieces seem to take mean nothing.
Lesson four starts making the connection between the meaninglessness of all the separate things we see in the world and all the separate thoughts we have. The bottom line is that everything, whether perceived as real or imagined, is meaningless in its separateness.
You can see a table and have an impression of it. You can then think of the same table and have a different impression of it. These broken impressions (forms) that didn't come together as the one definitive view are meaningless apart. Not seeing "the whole picture" is our excuse for inaction or for mistakes.
Again, as part of the lesson, we need only acknowledge, or profess, that this is the case, that we are the cause of the fragmented world we see. We'll eventually be led to seeing in a different way that will show us the true meaning behind everything we see.
Aaron