“Sunshine” is a metaphor for happiness that illustrates how it may make someone else’s day better, as in the expression “You are my sunshine.” According to a citation from Buddha, pleasure is like a candle that can light thousands of others.
Similes and metaphors are not the same. Similes compare two things, whereas metaphors claim that one thing is another.
A Chinese adage compared happiness to “a sunbeam,” Henry Grove compared it to “a pleasant stream,” and Alphonse Karr compared it to game that a rifle can miss if it is pointed at it too far away. These are only a few examples of happiness metaphors.