Being alert to danger even in times of peace
This idiom first appeared in Zuo Zhuan (Zuo's Commentary on the Spring and Autumn Annals), a book believed to be written by the historian Zuoqiu Ming (556-451 BC). It is a far-sighted vision that calls on people to be prepared for potential danger and urges the rulers to reflect on their political philosophy. It also encourages the people to maintain an enterprising spirit.
At the first meeting of the National Security Commission under the 19th CPC Central Committee held in April 2018, Xi Jinping said: The road ahead will not be plain sailing. The brighter the prospects, the more we should increase our awareness of potential dangers, raise our vigilance, and fully understand and effectively address major risks and challenges. We must prevent internal and external risks and challenges from interacting, combining and accumulating, so as to constantly improve our national security.
居安思危
“居安思危”出自《左传》，意为处在安宁的环境中，要想到可能出现的危难。这是一种长远、积极的忧患意识，告诫人们要随时有应对意外事件的思想准备。“居安思危”不仅成为历代有为的执政者时时警醒自己的政治理念，也是民众积极进取的一种精神体现。
2018年4月，习近平在十九届中央国家安全委员会第一次会议上指出，前进的道路不可能一帆风顺，越是前景光明，越是要增强忧患意识，做到居安思危，全面认识和有力应对一些重大风险挑战，着力防范各类风险挑战内外联动、累积叠加，不断提高国家安全能力。