All things must pass
Nothing lasts forever.
From the Bible, Matthew 24:6-8 (King James Version):
And ye shall hear of wars and rumours of wars: see that ye be not troubled: for all these things must come to pass, but the end is not yet.
For nation shall rise against nation, and kingdom against kingdom: and there shall be famines, and pestilences, and earthquakes, in divers places.
All these are the beginning of sorrows.
George Harrison used the phrase for the title of his successful 1970 triple album. The graphics from the subsequent CD release convey the phrase's meaning.
See also: the List of Proverbs.