It reflects the temporary nature, or ephemerality, of the human condition — that neither the negative nor the positive moments in life ever indefinitely last.
The general sentiment of the adage is found in wisdom literature throughout history and across cultures, but the specific phrase seems to have originated in the writings of the medieval Persian Sufi poets.
It is impossible to imagine a thought more truly and universally applicable to human affairs than that expressed in these memorable words, or more descriptive of that perpetual oscillation from good to evil, and from evil to good, which from the beginning of the world has been the invariable characteristic of the annals of man, and so evidently flows from the strange mixture of noble and generous with base and selfish inclinations, which is constantly found in the children of Adam.
[7] On September 30, 1859, Abraham Lincoln recounted a similar story: It is said an Eastern monarch once charged his wise men to invent him a sentence, to be ever in view, and which should be true and appropriate in all times and situations.
[7] Attar records the fable of a powerful king who asks assembled wise men to create a ring that will make him happy when he is sad.