I didn't realize what a large subject I opened up when I started researching phrasal verbs as metaphors. I'm now reading "Metaphors We Live By" by George Lakoff and Mark Johnson". I'm only on Chapter 5 so far. This is not a long book but it's not a quick-and-easy beachside read. Each page brings insights I need to pause and think about.
The values of our culture shape our language. Since the values are embeded in our language, our language helps shape the values of the children learning to speak, too!
For example we think:
More is up. Less is down.
Good is up. Bad is down.
More is better. Less is worse.
Up is better. Down is worse.
The future is ahead. The past is behind.
But in some cultures, the future is behind!