John Calvin Commentary James 4:14

"whereas ye know not what shall be on the morrow. What is your life? For ye are a vapor, that appeareth for a little time, and then vanisheth away." — James 4:14 (ASV)

For what is your life? He might have checked this foolish presumption in determining what is to come by many other reasons, for we see how the Lord daily frustrates those presumptuous men who promise what great things they will do.

But he was satisfied with this one argument: who has promised you a life for tomorrow? Can you, a dying man, do what you so confidently resolve to do?

For he who remembers the shortness of his life, will have his audacity easily checked, so as not to extend too far his resolves. No, for no other reason do ungodly men indulge themselves so much, but because they forget that they are men.

By the comparison to vapor, he strikingly shows that the purposes which are founded only on the present life are altogether fleeting.