This is part of a letter from Nelson Mandela to Winnie Mandela and from the first page of Mr. Mandela’s Conversations With Myself.
…the cell is an ideal place to learn to know yourself, to search realistically and regularly the process of your own mind and feelings. In judging our progress as individuals we tend to concentrate on external factors such as one’s social position, influence and popularity, wealth and standard of education. These are, of course, important in measuring one’s success in material matters and it is perfectly understandable if many people exert themselves mainly to achieve all these. But internal factors may be even more crucial in assessing one’s development as a human being. Honesty, sincerity, simplicity, humility, pure generosity, absence of vanity, readiness to serve others–qualities which are within easy reach of every soul–are the foundation of one’s spiritual life. Development in matters of this nature is inconceivable without serious introspection, without knowing yourself, your weaknesses and mistakes. At least, if for nothing else, the cell gives you the opportunity to look daily into your entire conduct, to overcome the bad and develop whatever is good in you.