“[U]sefulness is happiness, and... all other things are but incidental.”

“It's not what happens to you, but how you react to it that matters.”

“The happiness which is lacking makes one think even the happiness one has unbearable.”

“Be happy. Talk happiness.”

“Satisfaction of one's curiosity is one of the greatest sources of happiness in life.”

“Happiness is the interval between periods of unhappiness.”

“It is only to the happy that tears are a luxury.”