There is no sadder sight than a young pessimist.
Sadness gives depth. Happiness gives height. Sadness gives roots. Happiness gives branches. Happiness is like a tree going into the sky, and sadness is like the roots going down into the womb of the earth. Both are needed, and the higher a tree goes, the deeper it goes, simultaneously. The bigger the tree, the bigger will be its roots. In fact, it is always in proportion. That's its balance.
Every human walks around with a certain kind of sadness. They may not wear it on their sleeves, but it's there if you look deep.
Every man has his secret sorrows which the world knows not; and often times we call a man cold when he is only sad.
Sometimes we get sad about things and we don't like to tell other people that we are sad about them. We like to keep it a secret. Or sometimes, we are sad but we really don't know why we are sad, so we say we aren't sad but we really are.