Making proper use of impressions

A couple of times in the Discourses (2.9.15 and 2.19.13), Epictetus acknowledges the orthodox Stoic doctrine that virtue is the only genuine good, and vice the only genuine evil. Otherwise, he teaches that goods are a 'moral character (prohairesis) in the right condition,' and 'making proper use of impressions.'

Below is knowledge of Epictetus' chief rule (kanon) and exercise (askesis): making proper use of impressions.

This is from a message of 06/20/2018 from Grant C. Sterling to the International Stoic Forum:

"I receive impressions. For the moment, let [us] take
these as being out of our control. Those impressions are
cognitive, propositional--they are not uninterpreted raw data,
but rather ideas that claim that the world is a certain way.
I do not see a collection of colors and patterns--I "see"
my backpack sitting on the chair in front of my desk. Some
of these impressions are value-neutral (as that one is--there
is nothing good or bad about my backpack being on my chair).
But other impressions have a value component. Suppose that I
remember having left my backpack on the floor when I left--
I might now have the impression "my backpack is on my chair,
which means someone has intruded on my office, which is a very
bad thing!"
As I said, for the time being we are assuming that
these impressions are not in our control. But what _is_ in our
control is how we react to them. We can assent, or not assent.
That is, we can accept that a given impression is _true_, or
reject it as unproven or false. (Rejecting it as false involves
both refusing to assent to the impression AND formulating a
new idea (the opposite of the impression) and assenting to
that.) A few minutes ago, I assented to the impression that
my backpack was on the chair. I didn't have to, but I did.
The process of assenting is cognitive (it's something
that happens in the conscious mind), but is very seldom
explicit. By that I mean that, for example, although I assented
to the impression that my backpack was on the chair, at no time
did I formulate the explicit mental thought "It seems to me that
my backpack is on the chair. Should I assent to that impression?
yes, I think I will." My acceptance of the impression was so
simple and momentary that it seems as though things just passed
directly from impression to belief. But that isn't the way it works.
(Imagine a scenario where my backpack being there would be very
unexpected, and you can see how it would be possible for me to
question what my senses seem to be saying. I _could_ question them
even now (and really committed skeptics about the senses might be
able to do this in ordinary cases), I just don't.)
If I refuse to assent to an impression, nothing happens.
No emotion, no action, nothing.
If I assent to an impression with a value component, then
a desire will result. I will desire that the "good" thing happen,
or desire that the "bad" thing not happen. If the impression says
that this outcome has _already_ occurred, then a emotion will result
(in the example above, the likely emotions are anger or fear):
positive feelings of mental enjoyment if the impression was that
something good had happened, negative feelings if it was "bad".
Further, this may lead to another impression, assenting to
which will lead me to some course of action. For example, I might have
the further thought "It would be good for me to go find out who
has been in my office", and if I assent to this further idea then
I will stalk angrily down the hall to demand an explanation.

"All of this sounds complicated, but it boils down to this:
_everything_ on the Stoic view comes down to assent to impressions.
Choosing whether or not to assent to impressions is the only thing
in our control...and yet, everything critical to leading the best
possible life is contained in that one act. All our desires, all
our emotions, all our actions are tied to assenting to impressions.
If I get my assents right, then I have guaranteed eudaimonia. If
I get one wrong, I cannot have eudaimonia" (Grant C. Sterling).

Making correct use of impressions