We all know that nothing lasts forever. When first falling in love - and in the special rare cases where it lasts, for several decades afterward - we have the gut feeling that it will last forever. Marriage, if we go down that road, makes this explicit. But rationally, we know that one day, one of us, then the other, will die.
Those fancy renovations on the house we buy together, part of us thinks they'll be a permanent improvement in our lives. But one day we'll get sick of the colour and repaint, or we'll sell the house, and surely, one hopefully distant day, the whole building will be rubble. An artist's life's work, her greatest masterpiece, will one day be dust, or worse, forgotten. We make investments with time and money for the future, building a foundation for the lives of our future selves, our children, our grandchildren, our grandchildren's children, ad perputuum. But we know now more than ever that banks collapse, dynasties end, nations crumble. One good nuclear war, or one good blast from some unimaginable future weapon, and seven billion lifetimes of preparing for forever are sunk.
Let's float up to an even wider view. This planet, this solar system, this galaxy, they're just tiny drops in the pond of the universe. We don't know if time flows off forever into the past and the future, but we do know that the parts relevant to life as we understand it were formed at a definite starting point and, unless something drastic happens, have a definite end point. In between, any number of unknowns could cause a ripple in spacetime that washes our galaxy into the same irrelevance it had before it was formed. There is no room for forever in our universe.
We're left, then, with the conclusion that when someone expresses that something - anything - is forever, they are making a poorly reasoned guess at best, and outright lying at worst. What's incredible is that we even have a word for it, and that we can even fathom the concept in our minds. It's one of those words, like forever's cousin infinity, that is immediately understandable on the surface but a terrifying void underneath. Like swimming out too far in the sparkling ocean and suddenly there's just blackness all the way down. We invent ways to allay this terror - marriage, religion*, the afterlife - but it's just maintaining that surface illusion. Perhaps a necessary illusion - would we ever start to create anything if we knew it would soon be gone? - but an illusion nonetheless.
"If what they say is, 'nothing is forever,' then what makes (what makes), what makes (what makes), love the exceeeption."----------
--Outkast, Hey Ya!
* Footnote: Buddhism excepted.
Related uplifting post: Coffee and the heat death of the universe.