TΟ ΔΙAΛΥΘEΝ that which is disintegrated, unwound, and scattered (Note: the definite article)
TΟ AΝAΙΣΘΗTΟΥΝ that which lacks perception
I want to point out that I prefer "that" here rather than "one who" or any similar words. Once one dies, the body is an "it" since it is officially an inanimate object.
TΟ ΔΙAΛΥΘEΝ that which is disintegrated, unwound, and scattered (Note: the definite article)
TΟ AΝAΙΣΘΗTΟΥΝ that which lacks perception
I want to point out that I prefer "that" here rather than "one who" or any similar words. Once one dies, the body is an "it" since it is officially an inanimate object.
I also think "that" is to be preferred because I am reading the disintegrated body as having been a soul, but not necessarily the human form, which is still intact many weeks after the disintegration of the fragile, material soul.
I picture an atomic body that has been reduced to its constituent atoms, so, for me, words like "disintegrate" or "scattered" are robust descriptions of a dying soul that disperses from the body like a fart dissipating into the air, but when I imagine an entire human form, one of the first things that come to mind is a skeleton that can be perfectly preserved in a geometrically complete form for hundreds of millions of years, the same being true of teeth, and, if anthropologists and archaeologists get lucky, very, very tight, very dry skin. We also observe cultures (I believe I am thinking of a group in Indonesia) who mummify their relatives and un-earths them for yearly celebrations. "Disintegrating" or "Scattering" are definitely correct translations (I like disintegrate, myself), particularly because of their implication of a breakdown of a compound into uncuttables, but, in my mind, at least, a sizable % of the mass of a body not only does not disintegrate, but it maintains its recognizable form for, potentially, hundreds of millions of years.
Additionally, since the death that Epicurus observes is a description of an animal that perishes (including non-human animal)s, and since we rarely use the word "who" when identifying individual, non-human animals, employing "that" provides a biological consistency (especially if there are struggling humanoids on other planets).
a dying soul that disperses from the body like a fart dissipating into the air,
I don't know if I'd come up with that metaphor, but, yeah, like that.
There is a thread on the discussion of the translation of Principle Doctrine 2 over here: 
A Death in no way exists for us; for that which has dissolved is imperceptible; and that which is imperceptible in no way exists for us. [see: Key Doctrine 2]
or at least:
B Death in no way exists for us; for that which has dissolved lacks perception; and that which lacks perception in no way exists for us. [see: Key Doctrine 2]
It comes down to how we want to read το διαλυθέν αναισθητει
το - (art. sing. acc.) a, the, and occasionally that which or what [is]
διαλυθέν -(v. aor. pass. nom. sing.) to loosen, dissolve, divorce, discharge, break off, weaken
αναισθητει - a declension of ἀναίσθητος from ἀν- (an-, “not”) + αἴσθησις (aísthēsis, “sensation”) meaning without sense or feeling, without perception, not perceptible by sense.
I take the subject of the sentence to be "that which has dissolved", which is the atomized soul, so we're not talking about (as I read it) the experience of our friends dying, and what that means to us, we're exploring what it would mean for myself to be dead, or what death excludes.
So, I don't like the first translation (personally), because it seems redundant to say "Those who survive will no longer visually witness those who have died". It would be more prudent to express the idea that "Those who have died are definitely not experiencing an afterlife."
It would be more prudent to express the idea that "Those who have died are definitely not experiencing an afterlife."
Yes I definitely think that's the primary take-home point of the whole thing, as per what is said in the letter to Menoeceus:
Become accustomed to the belief that death is nothing to us. For all good and evil consists in sensation, but death is deprivation of sensation. And therefore a right understanding that death is nothing to us makes the mortality of life enjoyable, not because it adds to it an infinite span of time, but because it takes away the craving for immortality.
The tricky part to me is that PD02 seems to be focusing on deprivation of sensation in a somewhat different way than the letter - making a deeper point about the relationship between sensation and being alive.
I don't think we've addressed the question, sort of like the sorites question, of "How many faculties can you subtract from a human and still have something that is alive? I tend to think that "sensation" is sometimes being used not only to refer to the five senses but also to pain and pleasure and prolepsis.
Can you still have pain or pleasure or prolepsis without having any of the five bodily senses? I think it makes a considerable difference whether the answer is (A) once the five senses are gone you are dead or (B once the five senses AND pain and pleasure AND prolepsis is gone you are dead.
The implication of the standard translation of that last clause as "and that which lacks perception in no way exists for us" may tend to make some people think that any absence of all of the five senses equals death, but I am not sure at all that that is correct unless we also specify that feeling (pain and pleasure) and prolepsis are also gone. Being "unconscious" might suspend the five senses, but would not equal a state that is "nothingness" in the same way that death would. Or would it?
Opinions on any of that?
Here is an interesting article, and there may be others with more science details:
"Clinically dead".
So, not dead then. It still surprises me that our use of language concerning something as important as death is so reckless.
....more science details:
While I certainly am interested in the latest science, I wouldn't want us to go in that direction primarily. We need to understand where Epicurus was going because his view of death is going to relate to his view of life and how to spend it, as well as his views on reductionism/skepticism. The issue is not how long it takes our bodies to irreversibly decompose, the issue is whether after that period of time (no matter how long it is) we have "souls" which continue to live on in perpetuity.
Yes, there is a certain point at which you are dead, and the neurons stop firing.
Regarding the word "death" - first of all we see death in movies but often times it isn't depicted realistically --sometimes the person either dies peacefully or suddenly or the pain is minimized.
Also, some people may cognize "death" as a verb and a process - for example "he had a painful death".
And it is important to think about how Epicurus was talking about the state of being dead - so to rephrase it: "once we are dead, that state of being is nothing to us,..."
And here is something to consider: I think there could be a parallel between the experience of birth compared to the experience of death. Often when a person dies they have knowledge and sentient awareness which is different than when a baby is born, and yet there is a process that must occur which takes time and is passage into death.
Another article, here is an excerpt:
Although death has historically been medically defined as the moment when the heart irreversibly stops beating, recent studies have suggested brain activity in many animals and humans can continue for seconds to hours. In 2013, for instance, University of Michigan neurologist Jimo Borjigin and team found that rats’ brains showed signs of consciousness up to 30 seconds after their hearts had stopped beating. “We have this binary concept of life and death that is ancient and outdated,” Parnia says.
My belief, and after reading the article -- if you've lived a wise and pleasant life, there isn't anything to fear about the 30 seconds (or however long it takes) for consciousness to fully dissipate.
