**21.  He who is acquainted with the natural limits of life understands that those things that remove the pain that arises from need, and those things which make the whole of life complete, are easily obtainable, and that he has no need of those things that can only be attained with trouble.**

Alternate Translations: Bailey:  He who has learned the limits of life knows that that which removes the pain due to want and makes the whole of life complete is easy to obtain; so that there is no need of actions which involve competition.  Strodach:  One who understands the limits of the good life knows that what eliminates the pains brought on by need and what makes the whole of life perfect is easily obtained, so that there is no need for enterprises that entail the struggle for success.

NewEpicurean Commentary: An understanding of Nature leads us to see that the things which Nature requires — those things that remove physical pain — are easy to obtain, and are all that are needed to furnish a complete and optimal life.  Thus the man who understands the laws of Nature no longer desires those things which are more trouble to obtain than they are worth.