"Life is but a vapor" means human life is fleeting, fragile, and temporary—like morning fog that quickly vanishes.
This metaphor emphasizes that life is short, unpredictable, and ultimately under Mother Nature's control, serving as a call to live with purpose and eternal perspective, and focusing on lasting impact. It warns against arrogance and presumption, advocating for humility.
It is famously quoted from James 4:14: “Yet you do not know what your life will be like tomorrow. You are just a vapor that appears for a little while and then vanishes away.”
- From online sources with some editing 
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There was a discussion on another forum a couple days ago, about funny English translation of a few famous Chinese people and their famous words, including 曹操 and his words: “对酒当歌，人生几何!”. The translation made fun of his words as "Face to wine and sing a song, life is how long" 
I ain't an expert in 古诗词, my head hurts whenever thinking about 诗韵. But I can feel 曹操's emotion from the poem, and think what he meant was: "Drink & shout, life is too short!", especially considering what he said next: "譬如朝露，去日苦多."
Then, when I searched for a good English phrase about life being short, I found not only one from the Good book as above, but also one from the Bard, in his play King Henry IV: “The time of life is short; To spend that shortness basely were too long.”
So, from East to West, from the Bible to 曹孟德 to Shakespeare, the wisdom is so amazingly the same: "Life is but a vapor." And I think that ain't just for individuals, but for humans as a whole.
When I was writing this, Chip the bear, who with an attitude, nodded sympathetically, as he might outlive all of us. 
But there's nothing to be sad about. Let's live and live positively. As even "in this dystopian world", it's better to have lived and lost than never to have lived at all! 
Wish All a good and happy weekend!
