Book Three of On the Nature of Things explored mind, soul, and body, and closes with a discussion of why we should not fear death. I found much that I agreed with in this section.
Lucretius seems to anticipate a form of panexperientialist physicalism, because he believes that soul and mind are tiny particles spread throughout the body -- "Thus soul entire must be of smallmost seeds,/Twined through the veins, the vitals, and the thews."
He persuasively argues that soul and mind cannot exist without the body and that the body cannont exist without the soul and mind -- "Again, the body's and the mind's live powers/Only in union prosper and enjoy;/For neither can nature of mind, alone of itself/ Sans body, give the vital motions forth;/ Nor, then, can body, wanting soul, endure/ And use the senses."
And persuasively why they are mortal. One wonders why a distinct and immortal soul ever persisted in Western thinking or took such a drastically wrong turn with Descartes.
I enjoyed his humour here: "Again, at parturitions of the wild/ And at the rites of Love, that sould should stand/ Ready hard by seems ludicrous enough."
On the fear of death, he was direct. I too have never understood why people fear death. I can understand why they might fear the process of dying, as for many this is painful and horrible. But the state of death itself does not, to me, seem something to fear. Lucretius writes, "Therefore death to us/ Is nothing, nor concerns us in the least,/ Since nature of mind is mortal evermore." For him the only reason you would fear death is if you thought the soul was immortal, which has just disproven. This is direct, "Nothing for us there is to dread in death,/ No wretchedness for him who is no more."
He also anticipates Locke's view of personal identity here, "And, even if time collected after death/ The matter of our frames and set it all/ Again in place as now, and if again/ To us the light of life were given, O yet/ That process too would not concern us aught,/ When once the self-succession of our sense/ Has been asunder broken."
Book Three closes with a denunciation of prolonging life:
Nor by prolonging life
Take we the least away from death's own time,
Nor can we pluck one moment off, whereby
To minish the aeons of our state of death.
Therefore, O man, by living on, fulfill
As many generations as thou may:
Eternal death shall there be waiting still;
And he who died with light of yesterday
Shall be no briefer time in death's No-more
Than he who perished months or years before.
A refreshingly straight-forward rationalism.