Before birth, after death
On the axis: Death · the one who dies
We do not mourn the non-being that came before our birth: why dread the one that will follow our death? And how could death be an evil if no one is left to suffer it?
Justification
The argument rests on two premises drawn from physics: all good and evil reside in sensation, and death, the dissolution of the soul's atoms, is precisely the total privation of sensation. It follows that death can be an evil for no one, since the subject who would suffer it never coexists with it: while we are, it is not present; when it is present, we are no more. The fear of dying therefore targets a nothingness, and to dread a state in which one will not be is as empty as grieving over the time before one's birth. This reasoning, the second plank of the , removes the object of the anxiety that, on Epicurus' view, poisons the whole of life.
Death is nothing to us; for so long as we exist, death is not with us, and when death comes, then we do not exist.Letter to Menoeceus, 125
Letter to Menoeceus, 124-125 · Principal Doctrines, II
Justification
Since the soul is corporeal and is born, grows and ages with the body, it dissolves with it: all feeling then ceases, and a subject who is no more can suffer no evil. Death is therefore nothing to us, a conclusion Epicurus already held; but Lucretius devotes the whole of book III to it and makes of it a long consolation, multiplying proofs of the soul's mortality and the symmetry argument: we do not grieve over the nothingness before our birth, so why dread the one after our death, which resembles it in all things? To wish to survive is to contradict oneself, for the dead will have neither lack nor regret. The consolation widens into a rejoinder spoken by nature herself, who reproaches the living for their ingratitude and their thirst to endure.
Death, then, is nothing to us and touches us not at all, since the nature of the mind is held to be mortal.On the Nature of Things, III, 830-831
On the Nature of Things, III, 417-829 (the mortal soul; death is nothing to us) · On the Nature of Things, III, 830-1094 (the symmetry argument; the diatribe of Nature)