Dale Texas:
"All there is to know." = The total of all knowledge about something or someone "All there is to say." = The total of all possible comments about something or someone
Can you (meaning any person) ever possess all knowledge or predict all possible comments (which are uttered, said) and stop the conversations even into the future by other people?
Of course not.
You can never know all, about the moon, this, that, or anything you can imagine. You can never say all, about the moon, this, that, or anything you can imagine.
Q.You can never say what?
A. You can never say all there is to say about anything!
You would be delusional to think otherwise.
Does that help?
I'd be thankful if you'd let me know the meaning and grammatical construction of "stop the conversations even into the future by other people".