We tend to project our own internal state onto the world; for example, someone feeling anxious may perceive others as being hostile.
What we judge or find repulsive in others often represents a "shadow" part of ourselves that we haven't fully accepted or integrated.
On a simpler level, humans naturally mirror the mannerisms and emotions of those around them to build rapport and show cooperation.
Understanding that others suffer from the same insecurities as we do can lead to deeper compassion and more conscious relating.
Were you referring to the of people as mirrors, or did you just finish watching the 2004 film ?