Peace of mind if not some superficial state of being, it is the very foundation of how to do and feel about everything. Whatever you do that produces peace of mind is good, and whatever you do that destroys it is bad. Knowledge, resources, planning, these are all means towards the end of satisfying peace of mind.
There are three ways to maintain and cultivate peace of mind. Physical quietness and harmony is simple to achieve and the most evident one. Mental quietness, in which one has no wandering thoughts at all, is more difficult, and it is the central point of meditation. But that quietness, in which one is in peace with his desires and choices, that seems to be the hardest.
You can witness peace of mind in the work of skilled craftsmen and artisans. To say that skilled craftsmen are not artists is to misunderstand the nature of art. There is an harmony with their work that has no actor or subject. The material and the craftsmen’s thoughts change simultaneously in a progression completely smooth and congruent until his mind is at peace at the exact moment that the job is done.