The following is from Epicurus' Letter to Herodotus.
Next, keeping in view our perceptions and feelings (for so shall we have the surest grounds for belief), we must recognize generally that the soul is a corporeal thing, composed of fine particles, dispersed all over the frame, most nearly resembling wind with an admixture of heat, in some respects like wind, in others like heat. But, again, there is the third part which exceeds the other two in the fineness of its particles and thereby keeps in closer touch with the rest of the frame. And this is shown by the mental faculties and feelings, by the ease with which the mind moves, and by thoughts, and by all those things the loss of which causes death. Further, we must keep in mind that soul has the greatest share in causing sensation. Still, it would not have had sensation, had it not been somehow confined within the rest of the frame. But the rest of the frame, though it provides this indispensable conditions for the soul, itself also has a share, derived from the soul, of the said quality; and yet does not possess all the qualities of soul. Hence on the departure of the soul it loses sentience. For it had not this power in itself; but something else, congenital with the body, supplied it to body: which other thing, through the potentiality actualized in it by means of motion, at once acquired for itself a quality of sentience, and, in virtue of the neighborhood and interconnection between them, imparted it (as I said) to the body also.
Hence, so long as the soul is in the body, it never loses sentience through the removal of some other part. The containing sheaths may be dislocated in whole or in part, and portions of the soul may thereby be lost; yet in spite of this the soul, if it manage to survive, will have sentience. But the rest of the frame, whether the whole of it survives or only a part, no longer has sensation, when once those atoms have departed, which, however few in number, are required to constitute the nature of soul. Moreover, when the whole frame is broken up, the soul is scattered and has no longer the same powers as before, nor the same notions; hence it does not possess sentience either.
For we cannot think of it as sentient, except it be in this composite whole and moving with these movements; nor can we so think of it when the sheaths which enclose and surround it are not the same as those in which the soul is now located and in which it performs these movements.
There is the further point to be considered, what the incorporeal can be, if, I mean, according to current usage the term is applied to what can be conceived as self-existent. But it is impossible to conceive anything that is incorporeal as self-existent except empty space. And empty space cannot itself either act or be acted upon, but simply allows body to move through it. Hence those who call soul incorporeal speak foolishly. For if it were so, it could neither act nor be acted upon. But, as it is, both these properties, you see, plainly belong to soul.
Accustom yourself to believe that death is nothing to us, for good and evil imply awareness, and death is the privation of all awareness; therefore a right understanding that death is nothing to us makes the mortality of life enjoyable, not by adding to life an unlimited time, but by taking away the yearning after immortality. For life has no terror; for those who thoroughly apprehend that there are no terrors for them in ceasing to live.
Foolish, therefore, is the person who says that he fears death, not because it will pain when it comes, but because it pains in the prospect. Whatever causes no annoyance when it is present, causes only a groundless pain in the expectation. Death, therefore, the most awful of evils, is nothing to us, seeing that, when we are, death is not come, and, when death is come, we are not. It is nothing, then, either to the living or to the dead, for with the living it is not and the dead exist no longer. But in the world, at one time people shun death as the greatest of all evils, and at another time choose it as a respite from the evils in life. The wise person does not deprecate life nor does he fear the cessation of life. The thought of life is no offense to him, nor is the cessation of life regarded as an evil. And even as people choose of food not merely and simply the larger portion, but the more pleasant, so the wise seek to enjoy the time which is most pleasant and not merely that which is longest. And he who admonishes the young to live well and the old to make a good end speaks foolishly, not merely because of the desirability of life, but because the same exercise at once teaches to live well and to die well. Much worse is he who says that it were good not to be born, but when once one is born to pass with all speed through the gates of Hades. For if he truly believes this, why does he not depart from life? It were easy for him to do so, if once he were firmly convinced. If he speaks only in mockery, his words are foolishness, for those who hear believe him not.
Lucretius was a Roman poet and an Epicurean. The following is from book III of his poem De Rerum Natura (On the Nature of Things), in an unfortunately archaic translation by William Ellery Leonard
Hence, where thou seest a man to grieve because When dead he rots with body laid away, Or perishes in flames or jaws of beasts, Know well: he rings not true, and that beneath Still works an unseen sting upon his heart, However he deny that he believes. His shall be aught of feeling after death. For he, I fancy, grants not what he says, Nor what that presupposes, and he fails To pluck himself with all his roots from life And cast that self away, quite unawares Feigning that some remainder's left behind. For when in life one pictures to oneself His body dead by beasts and vultures torn, He pities his state, dividing not himself Therefrom, removing not the self enough From the body flung away, imagining Himself that body, and projecting there His own sense, as he stands beside it: hence He grieves that he is mortal born, nor marks That in true death there is no second self Alive and able to sorrow for self destroyed, Or stand lamenting that the self lies there Mangled or burning. For if it an evil is Dead to be jerked about by jaw and fang Of the wild brutes, I see not why 'twere not Bitter to lie on fires and roast in flames, Or suffocate in honey, and, reclined On the smooth oblong of an icy slab, Grow stiff in cold, or sink with load of earth Down-crushing from above. "Thee now no more The joyful house and best of wives shall welcome, Nor little sons run up to snatch their kisses And touch with silent happiness thy heart. Thou shalt not speed in undertakings more, Nor be the warder of thine own no more. Poor wretch," they say, "one hostile hour hath ta'en Wretchedly from thee all life's many guerdons," But add not, "yet no longer unto thee Remains a remnant of desire for them" If this they only well perceived with mind And followed up with maxims, they would free Their state of man from anguish and from fear. "O even as here thou art, aslumber in death, So shalt thou slumber down the rest of time, Released from every harrying pang. But we, We have bewept thee with insatiate woe, Standing beside whilst on the awful pyre Thou wert made ashes; and no day shall take For us the eternal sorrow from the breast." But ask the mourner what's the bitterness That man should waste in an eternal grief, If, after all, the thing's but sleep and rest? For when the soul and frame together are sunk In slumber, no one then demands his self Or being. Well, this sleep may be forever, Without desire of any selfhood more, For all it matters unto us asleep. Yet not at all do those primordial germs Roam round our members, at that time, afar From their own motions that produce our senses- Since, when he's startled from his sleep, a man Collects his senses. Death is, then, to us Much less- if there can be a less than that Which is itself a nothing: for there comes Hard upon death a scattering more great Of the throng of matter, and no man wakes up On whom once falls the icy pause of life. This too, O often from the soul men say, Along their couches holding of the cups, With faces shaded by fresh wreaths awry: "Brief is this fruit of joy to paltry man, Soon, soon departed, and thereafter, no, It may not be recalled."- As if, forsooth, It were their prime of evils in great death To parch, poor tongues, with thirst and arid drought, Or chafe for any lack. Once more, if Nature Should of a sudden send a voice abroad, And her own self inveigh against us so: "Mortal, what hast thou of such grave concern That thou indulgest in too sickly plaints? Why this bemoaning and beweeping death? For if thy life aforetime and behind To thee was grateful, and not all thy good Was heaped as in sieve to flow away And perish unavailingly, why not, Even like a banqueter, depart the halls, Laden with life? why not with mind content Take now, thou fool, thy unafflicted rest? But if whatever thou enjoyed hath been Lavished and lost, and life is now offence, Why seekest more to add- which in its turn Will perish foully and fall out in vain? O why not rather make an end of life, Of labour? For all I may devise or find To pleasure thee is nothing: all things are The same forever. Though not yet thy body Wrinkles with years, nor yet the frame exhausts Outworn, still things abide the same, even if Thou goest on to conquer all of time With length of days, yea, if thou never diest"- What were our answer, but that Nature here Urges just suit and in her words lays down True cause of action? Yet should one complain, Riper in years and elder, and lament, Poor devil, his death more sorely than is fit, Then would she not, with greater right, on him Cry out, inveighing with a voice more shrill: "Off with thy tears, and choke thy whines, buffoon! Thou wrinklest- after thou hast had the sum Of the guerdons of life; yet, since thou cravest ever What's not at hand, contemning present good, That life has slipped away, unperfected And unavailing unto thee. And now, Or ere thou guessed it, death beside thy head Stands- and before thou canst be going home Sated and laden with the goodly feast. But now yield all that's alien to thine age,- Up, with good grace! make room for sons: thou must." Justly, I fancy, would she reason thus, Justly inveigh and gird: since ever the old Outcrowded by the new gives way, and ever The one thing from the others is repaired. Nor no man is consigned to the abyss Of Tartarus, the black. For stuff must be, That thus the after-generations grow,- Though these, their life completed, follow thee; And thus like thee are generations all- Already fallen, or some time to fall. So one thing from another rises ever; And in fee-simple life is given to none, But unto all mere usufruct. Look back: Nothing to us was all fore-passed eld Of time the eternal, ere we had a birth. And Nature holds this like a mirror up Of time-to-be when we are dead and gone. And what is there so horrible appears? Now what is there so sad about it all? Is't not serener far than any sleep? And, verily, those tortures said to be In Acheron, the deep, they all are ours Here in this life. No Tantalus, benumbed With baseless terror, as the fables tell, Fears the huge boulder hanging in the air: But, rather, in life an empty dread of gods Urges mortality, and each one fears Such fall of fortune as may chance to him. Nor eat the vultures into Tityus Prostrate in Acheron, nor can they find, Forsooth, throughout eternal ages, aught To pry around for in that mighty breast. However hugely he extend his bulk- Who hath for outspread limbs not acres nine, But the whole earth- he shall not able be To bear eternal pain nor furnish food From his own frame forever. But for us A Tityus is he whom vultures rend Prostrate in love, whom anxious anguish eats, Whom troubles of any unappeased desires Asunder rip. We have before our eyes Here in this life also a Sisyphus In him who seeketh of the populace The rods, the axes fell, and evermore Retires a beaten and a gloomy man. For to seek after power- an empty name, Nor given at all- and ever in the search To endure a world of toil, O this it is To shove with shoulder up the hill a stone Which yet comes rolling back from off the top, And headlong makes for levels of the plain. Then to be always feeding an ingrate mind, Filling with good things, satisfying never- As do the seasons of the year for us, When they return and bring their progenies And varied charms, and we are never filled With the fruits of life- O this, I fancy, 'tis To pour, like those young virgins in the tale, Waters into a sieve, unfilled forever.