Danger: Clouds Crossing
Cloud Atlas paints a vivid metaphor of human souls as clouds, traveling across time. Sometimes they fade away and reform. Sometimes they combine into something new. Sometimes they look like bunnies.
The six main characters in Cloud Atlas, with their comet-shaped birthmarks, may or may not be reincarnations of one another. They share some traits and memories and experience echoes of other lives, past and future. Their souls travel, mingle with others, and eventually dissipate, like clouds.
Now, an atlas is a book of maps. You can map continents, state boundaries, and interstates, because those things are static—unless you live in Boston, where the streets change on a weekly basis. However, you can't map the clouds. They're fluid and always changing. A cloud atlas is an impossibility. It would be just as impossible to map out the lives of every person on the planet. To have a cloud atlas would mean that you could know the past and predict the future. And even though history repeats itself, it's never exactly the same.