From the greatest to the smallest, happiness and usefulness are largely found in the same soul, and the joy of life is won in its deepest and truest sense only by those who have not shirked life's burdens.
Whoever possesses abundant joy must be a good man: but he is probably not the cleverest man, although he achieves exactly what it is that the cleverest man strives with all his cleverness to achieve.
There is little that separates humans from other sentient beings - we all feel joy, we all deeply crave to be alive and to live freely, and we all share this planet together.