The principal thing to attain happiness, is to purify one's mind from all things that disturb it and create inharmony. There are not only bad impressions which disturb the tranquility of mind, but there are many feelings of resentment and resistance against things which do not agree with one's own idea which disturb one's mind. The person who has some business to carry out, some profession to attend to, requires a tranquil mind, but especially the one who journeys on the spiritual path needs tranquility of mind most. Prayers, concentrations, meditations make no effect when the mind is not purified from all disturbances.