Charles H. Spurgeon on Psalms 144:4

Man is like to vanity. Adam is like to Abel. He is like that which is nothing at all. He is actually vain, and he resembles that unsubstantial empty thing which is nothing but a blown up nothing, —a puff, a bubble. Yet he is not vanity, but only like it. He is not so substantial as that unreal thing; he is only the likeness of it. Lord, what is a man? It is wonderful that God should think of such a pretentious insignificance. His days are as a shadow that passeth away. He is so short lived that he scarcely attains to years, but exists by the day, like the ephemera, whose birth and death are both seen by the self same sun. His life is only like to a shadow, which is in itself a vague resemblance, an absence of something rather than in itself an existence. Observe that human life is not only as a shade, but as a shade which is about to depart. It is a mere mirage, the image of a thing which is not, a phantasm which melts back into nothing. How is it that the Eternal should make so much of mortal man, who begins to die as soon as he begins to live? The connection of the two verses before us with the rest of the psalm is not far to seek: David trusts in God and finds him everything; he looks to man and sees him to be nothing; and then he wonders how it is that the great Lord can condescend to take notice of such a piece of folly and deceit as man.