It’s crazy when you really think about it: every person you ever meet is essentially a mystery to you. How can we really know what is going on inside their minds? What they’re thinking, feeling, planning? How can we ever really understand what their behavior means, why they are motivated as they are, and even how they see and understand us?
Another person’s world is like a black box to us. All we have to go on are things outside of that black box—the words they say, their facial expressions and body language, their actions, our past history with them, their physical appearance, the tone and quality of their voice, and so on.