Aristotle taught that happiness, success and wisdom are often found in the moderate place between extremes. 

For example, courage is a mean between cowardice and rashness -- justice -- is a mean between man getting more or less than his due, and happiness is a mean found between inactive piousness and immoral activity. 

To be happy, he thought, most people needed to live virtuously in their private lives, be politically involved to influence the society and the future, and find ways to personally serve and give to those in need.

Such active balance is necessary for the maintenance of freedom and widespread prosperity.