And because of this, there is a timely aspect to art. It is of a moment. The original artwork is always receding from view as times change. Art touches on the timeless, but the artwork itself (much as we may wish to deny it) is time-bound.
At a certain point it disappears entirely, or is reconfigured into something which its original audience would find alien, or is kept around as an honored but increasingly baffling relic (we know this is important, but we're not longer sure why) that has an honored but fossilized place at the table, like a great-grandparent safely seated for Thanksgiving supper.
I've often thought this about comedy, in how it would be virtually impossible for humour to translate across multiple generations. References to pop culture, the way language and slang is used, the social issues of the day, all of these will eventually change, wiping out all of the short cuts a comedian must use to make his ideas and images cut through their delivery.
I used to take some solace in remembering my childhood relationship to Monty Python, and how I would find so much of it funny, even when they would mention obscure British parliamentarian figures or celebrities that I didn't know then (and still don't know now). And they still functioned since what I was actually laughing at was the sound of the names, and it was really more the musicality of language which I was responding to. The specific references really didn't matter. They were timeless. Or so I thought. But then I think of how our relationship even to the sound of language, its rhythms, the cadences, how we subliminally encode what specific kind of accents mean to us (will lower class or upper class ways of speaking in Britain remain consistent 100 years from now, will our impressions of the rich or the poor, the presumed educated or the uneducated nature of those ways of speaking still hold the same prejudices) and I realized even the basic operating tools of humor can't help but ultimately change.
And then I hear people talking about the immortality of artists once they really hit their A game, how they are now for the ages, and can only laugh at the complete hopelessness of such a thing. Really, the only joke that may still have a chance of being universally funny a thousand years from now (even though it is a joke I don't imagine many people other than me find terribly funny)