时光如沙漏却倒不转流年
[shí guāng rú shā lòu què dăo bù zhuăn liú nián]
Time Is Like an Hourglass but Cannot Turn Back the Flowing Years describes an awareness and acceptance of the irreversible passage of time and aging process. It conveys nostalgia for fleeting youth or precious moments in life that have passed by like grains slipping through the neck of an hourglass, while also emphasizing that once lost, they cannot return just by turning the hourglass back around.