Detachment
Detachment is a state in where a person becomes separated from his or her environment and its influence. It is an important principal in Buddhism, Zen philosophy, and Kabbalah. In psychology it is referred to as dissociation or apathy.
Lao Tzu's "Tao Te Ching" expressed the concept (in chapter 44) as:
Fame or Self: Which matters more? Self or Wealth: Which is more precious? Gain or Loss: Which is more painful? He who is attached to things will suffer much. He who saves will suffer heavy loss. A contented man is rarely disappointed. He who knows when to stop does not find himself in trouble. He will stay forever safe.