“a momentary perception”
Isn’t that a thing?
Heraclitus is saying that a momentary perception rests from change. Even a snapshot, motionless and dead, cannot exist, unless it rests from change.
No - memory is part of the measuring stick of change - not the fabricator of change. Recollecting, remembering, that seems like a distinct type of changing. So I’m not sure the fact of recollection as our means of tracking what we call “change” means “there is no change” or that “change is an illusion.”
Heraclitus’ point is universal, logical conclusion about things, not just a description of what is happening (clearly, because he describes the impossibility of stepping into a river).
But really, whether the contents of your consciousness are an illusion or they are direct perceptions of the real world, to distinguish this from that, to identify any one unit (like “a momentary perception”), is to conjure up a thing, which, according to Heraclitus, is to refer to that which rests from change.
If change is an illusion, than illusion is an illusion too. You have made the phenomena of change distinct from the phenomena of illusion. In learning about change, and then learning about illusion, you become the change, the arbiter what has moved from seeming change to actual illusion.
What things exist to allow one to distinguish realities like “a momentary perception”,or “a snapshot” from “the illusion of change”? Anything? If so, Heraclitus says what exists rests from change.
Admittedly Heraclitus does assume that change is already happening. If you don’t agree with that, then his notion of thinghood will remain unsatisfying, or, I will be unable to change your mind.
ADDED: Oddly, I don’t think we see the world too differently on this point - we are getting at a similar…thing. I would say that change is what makes things elusive. Because of this, people say “change is an illusion”. But I think this misstates a more clear notion of the difference between thinghood versus the existence of individual things.