Gandhi on Peace

In the words of Mahatma Gandhi:

"The greatest power in the world is that of the Soul. Peace is its highest expression. To attain peace, first we must acquire greater mastery over ourselves. We secure then an atmosphere of perfect peace, calm and goodwill that protects and fortifies ourselves and blesses others around us.”
(Discourses on the Gita)

"Peace requires one first to be brave enough to love 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.”
(Discourses on the Gita)

“True humility means most strenuous and constant endeavor, entirely directed towards the service of humanity. God is continuously in action without resting for a single moment. If we should serve him or become one with him, our activity must be as unwearied as his. There may be momentary rest in store for the drop which is separated from the ocean, but not for the drop in the ocean, which knows no rest. The same is the case with ourselves. As soon as we become one with the ocean in the shape of God, there is no more rest for us, nor indeed do we need rest any longer. Our very sleep is action. For we sleep with the thought of God in our hearts. This restlessness constitutes true rest. This never-ceasing agitation holds the key to peace ineffable. This supreme state of total surrender is difficult to describe, but not beyond the bounds of human experience. It has been attained by many dedicated souls, and may be attained by ourselves as well.”
(The Way to God)

“Without good thoughts there is no peace, and without peace there is no happiness. Where a stable-minded man sees things clear as daylight, the unstable man distracted by the turmoil of the world is as good as blind. On the other hand, what is pure in the eyes of the worldly wise looks unclean and repels the stable-minded man. Rivers continuously flow into the sea, but the sea remains unmoved; in the same way all sense objects come to the yogi, but he always remains calm like the sea. One who abandons all desires, is free from pride and selfishness and behaves as one apart, finds peace. This is the condition of a perfect devotee of God, and he who is established therein, even at the final hour, finds moksha… self-liberation.”
(Discourses on the Gita)

“He who would practice yoga, i.e., evenness of temper (samatvam), cannot but perform action. The man who has achieved such evenness of temper will be serene, because his mere thoughts are charged with the strength of action. A yogi is one who is not attached to the objects of sense or to action and whose mind has ceased to roam restlessly. He is a yogi who is a man of knowledge as well as experience, who is unwavering and master of his senses and to whom gold, stone and earth seem all alike. He regards with an equal eye friend and foe, sinner and saint. The yogi is stable-minded at all times, and is without effort free from all desires. He is like an unflickering lamp burning in a windless place. He is not tossed to and fro by dramatic events on the world-stage or by his own brain waves. Such mental poise can be achieved by slow but steady effort. The mind is fickle and restless, but it should be gradually stabilized, for one can have peace of mind only when he is firm of understanding. In order thus to stabilize the mind, he should constantly fix it on the Soul.“ 
(Discourses on the Gita)