If you wish to make a man your enemy, tell him simply, 'You are wrong.' This method works every time.

While one person hesitates because he feels inferior, the other is busy making mistakes and becoming superior.

Psychologically I should say that a person becomes an adult at the point when he produces more than he consumes or earns more than he spends. This may be at the age of eighteen, twenty-five, or thirty-five. Some people remain unproductive and dependent children forever and therefore intellectually and emotionally immature.