Productivity

一朝國祚可甚長，但若亡國，豈不只列為歷朝之一嗎？周雖歷七百餘年，貢獻無多。相反，秦歷僅十五年，卻統一中國，是為首大帝國。生命也是如此。重要的，不是壽命，乃是成就。

Translated, that means:
"A dynasty may last for some time, yet if it falls, is it not but listed as one dynasty? Even though Zhou lasted over 700 years, its contributions were limited. On the contrary, Qin lasted but 15 years, yet unified China, as the first great (Chinese) empire. So too is life. What is important is not longevity, but achievement."

Productivity - it's not how long you're at the job, it's what you manage to do with it. I guess the same could be said of school.