zǐ yuē wēn gù ér zhī xīn kě yǐ wéi shī yǐ
子 曰：‘‘温 故 而 知 新，可 以 为 师 矣’’
Confucius says:'if a man keeps cherishing his old knowledge,so as continually to be acquiring the new(or you can say :'learn the new while reviewing the old'),he may be a teacher of others'.
子：master，confusius or sometimes refers to his students.
故：old things or old friends（故人），here refers to old knowledge
矣：了，indicating an action accomplished.