On Arising and Ceasing.
"Monks, these three are fabricated characteristics of what is fabricated. Which three? Arising is discernible, passing away is discernible, alteration (literally, other-ness) of what stays is discernible. ..."
"Now these three are unfabricated characteristics of what is unfabricated. Which three? No arising is discernible, no passing away is discernible, no alteration of what stays is discernible. ..." [AN 3.47] http://www.accesstoinsight.org/tipitaka ... .than.html
Now, the process of seeing is constantly changing, everyone is aware of this.
But, the Buddha never says that seeing is impermanent, or suffering. Why?
Because seeing is not fabricated, it is not a sankhata. It does not cease while
one is alive. It does not need to cease. It is outside the scope of the teachings.
Nor are hearing, smelling, tasting, touching or cognizing fabricated things.
Only fabricated things are said to be impermanent, suffering and non-self.
Take, for example, "eye-consciousness", this is fabricated, it is something
which has been made, constructed. When it was first made, that is called its
arising. While it persists, that is called its staying. When it vanishes, that
is called its passing away.
It only arises once, for most of us this was many years in the past. It will
only pass away once, when we become enlightened. Between these events it
persists or stays.
When it is said that eye-consciousness is impermanent, this means that it can
pass away, or cease, that it is possible for it to vanish at any time.
And the same applies to all other fabricated things.
In the first passage above, where the Buddha speaks of fabricated things, he
is instructing his bhikkhus about what they should see in their own minds.
He is not speaking about his own mind, because, for him, all fabricated things
have passed away, and no new ones are being created.
In the second passage above, where the Buddha speaks of "what is unfabricated",
he is describing the absence of fabricated things, both in his own mind and in
the minds of other enlightened individuals.
Fabricated things are the "objects" that the mind is obsessed with. Therefore,
the absence of such obsessions implies the absence of any such objects. So the
enlightened mind is said to be "without any object."
But this only means without any object of obsession, there can still be sight
objects or cognized objects (thoughts).