The body is cleansed by soap and water, but true cleanliness can be achieved only from within. The cleansing of the body may keep physical illness away, but the disease of the mind requires inner cleanliness. A perfume applied to the body might please the company around, but good thoughts and sweet conversation will please them more for a long time. As the soap is for the body, truth is for the speech, both have a high cleansing effort. The mind has to be cleansed by proper education in the crucible of renunciation. Education is the process of gaining illumination - it is the light that dispels the darkness of ignorance and doubt.  It confers humility and discipline.   

- Divine Discourse, February 17, 1980.

The highest discipline is to bring about unity in one's thought, word and deed. - Baba