The Greatest power in the world is that of the Soul.  
Peace is its highest expression.  
To attain peace, 
first we must acquire great mastery over ourselves. 
We secure then an atmosphere of perfect peace, 
calm and goodwill 
that protects and fortifies ourselves 
and blesses others around us.

- Mahatma Gandhi

Peace requires one first to be brave enough to love another,
To tolerate another, and to trust another.  That requires faith in oneself.
One has not the strength to be peaceful if he is fighting the internal duel of selfish desires. 
Good can never result from evil desires or actions; hence the Gita's central
teaching of the oneness of the means and ends.  
The practice of peace is thus a test of the sincerity of our hearts; 
it requires solid and silent self-sacrifice, honesty and the capacity for diligent work,
but must be realized first in its source within.

- Mahatma Gandhi