一只手握不住流沙两双眼留不住落花
[yī zhĭ shŏu wò bù zhù liú shā liăng shuāng yăn liú bù zhù luò huā]
This has a philosophical undertone - just as you can't hold onto quicksand and can't stop falling flowers with your eyes, this reflects the transient nature of life and possibly missed opportunities or relationships.