An adult's sorrow is like a pill locked in a safe. When it can finally be shown to others, it is either an antidote, bringing a bright and sunny future, or poison, bringing everything to an end!
Sorrow is sorrow because it contrasts with its opposite, because only you can feel it, and because sorrow, by its very nature, is something only you can bear alone!
Theme: If extreme joy begets sorrow, then perhaps extreme sorrow brings happiness in turn.