Heraclitus, who has already changed to become like Michelangelo (according to Raphael). Image from Wikipedia
It was Heraclitus who famously proposed that you cannot step in the same river twice.
He worded it in a way that it is hard to tell whether it is the river that changed or you or both, but it doesn’t matter; the point is that everything is continually changing. Heraclitus lost his marbles later on, and decided to leave society to wander around the wilderness, eating grass and what not. Now, here is the tricky part. Something may be defined by its changing properties, which is the way Heraclitus saw it (a river is a river precisely because change is intrinsic to it), but that change may eventually turn things into something different and new. A student of Heraclitus, Cratylus took this last concept way too seriously, saying things change so damn much you could not step on the river even once, let alone twice. He was hardcore, so he proposed that you should not even mention the river, as it would have already changed. He did not have an issue with rivers alone, you should not mention anything. Consistent with his beliefs Cratylus gave up speaking, since what is the point of talking about something that has already changed. Instead he just pointed at things and made growling noises (at least I imagine him making growling noises). Maybe he could have taken the statement even further, but since he stopped talking we will never know. As you can see believing that things change way too much may lead to some mental issues.
On the opposite side of the spectrum let’s remember that… what’s his face? Parmenides? said “are you guys on crack?, can’t you see that nothing ever changes?” Apparently he did not have an exciting life, but at least he looked happier than Heraclitus, who was always moping around. Though not as happy as Democritus, who laughed like a hyena, even when nothing funny had happened.
And talking about Heraclitus, here is a tip if you want to become a famous writer (it worked for him). You leave your book at the Temple of Artemis, and then voilà, the hunter turns it into a bestseller. Too bad the temple is not there anymore, except for a few fragments and a column, so I guess you will not be famous, sorry. Now that I think about it, that temple was burned down by some idiot, so he could be famous and remembered (and it worked! We still know his name). He did not want to be famous as a writer or anything, but more in the way Youtube makes you famous, just for the sake of it. I won’t mention his name so I am not contributing to his goal, though I am aware it is too late for that (back then the Ephesians decreed that they would kill you if you mentioned his name). It is amazing how little things have changed (maybe Parmenides was right after all, nothing changes), as acting idiotic can still make you famous, just as it did thousands of years ago.
By the way, it was in fact Parmenides the one that proposed the being never changes, I just looked it up.