I never feel like I really know someone until I see them cry. Some people are "criers" and some aren't, but crying is a healthy, cathartic human emotion that every adult should be able to experience.
There's a lot of social and psychological baggage attached to crying, particularly for men, for whom it's associated with weakness and shame. For women it can be viewed as a sign of mental instability or hysteria.
But these are false social constructs that prevent lots of people from letting go and experiencing the power of healthy crying. It's when we cry, I think, that we can potentially access our deepest emotions and experience true growth. For the very same reason, we are often resistant to crying.
I'm at my best when a friend cries in front of me. I never offer them a tissue or otherwise draw attention to the fact that tears are falling. I'm usually too busy listening to what they're saying and seeing what it reveals. And I never feel closer to my own state of mind and body than when I cry.