The principal thing necessary for attaining happiness is to purify one's mind from all things that disturb it and create disharmony. There are not only bad impressions which disturb the tranquility of the mind, but many feelings of resentment and resistance against things which do not agree with one's own idea that disturb one's mind. For the person who has some business to carry on or some profession requires a tranquil mind, but the one who journeys on the spiritual path most needs tranquility of mind. Prayers, concentrations, meditations have no effect if the mind is not purified from all disturbances. Therefore for an adept no cost and no sacrifice is too great for keeping harmony within himself.