When we meet someone after several months, they tend to tell us about the changes that they notice in us. "Hey, you seem to have put on some weight!" 

However, we often don't perceive the same changes about us in that drastic way. 

This is because we see ourselves everyday and the smaller changes that occur day-to-day don't seem as big and often go un-noticed. 

If we take a moment to reflect, though, and think back to how things were a few months ago, we are able to spot that difference. 

The purpose of reflection is simply to replicate the effect of meeting someone after several months, and to notice the quantum of change that has occurred in ourselves about the things that we care about. 

Only if we can accurately spot what's happening can we determine whether the change is in a direction that we approve of and determine what we'd like to do about it if it isn't.