Lucretius, answered from the texts and cited to the page.
Death is nothing to us, and does not concern us a whit, because the nature of the mind is a mortal possession.1 That is the sentence on which the rest of the argument hangs, and I did not reach it by assertion. I reached it by proving first that the soul is born with the body and dies with it. It falls sick along with the diseases of the body, it is tormented by anxious thoughts of what is to come, it is worn out with care, and it is plunged at times into the dark waters of lethargy and forgetfulness.1
A thing that sickens and fails with the flesh cannot be linked to the everlasting; to join the mortal with the immortal, and think they can feel together and act one upon the other, is foolishness.1 The soul does not live apart from the body any more than the body lives apart from the soul. Hand and eye and nostril, sundered from us, cannot feel nor be, and are soon melted in corruption; so the mind cannot exist by itself without the body and the very man.2
Neither can produce the motions of life alone: bereft of soul the body cannot last on and feel, and the eye torn out by the roots cannot discern anything apart from the whole.2 Then I turn the reader to what he already knows. Look back over the immeasurable time that has gone before we were born, and see that it has been nothing to us. When the Carthaginians came from all sides to the shock of battle and all the world shuddered beneath the coasts of heaven, in doubt to whose sway all human power by land and sea must fall, we felt no ill, for we were not.3
Nature holds this up as a mirror of the time that is to come. When body and soul, by whose union we are made one, are parted, nothing at all can happen to us who then will be no more, no, not if earth shall be mingled with sea and sea with sky.3 Suppose someone answers that the soul may still have feeling after it is rent from the body. Even so, it is nothing to us, who are made one by the mating and marriage of body and soul.3
Suppose time gathered our substance together again after our death and set it back as it now stands. That too would not concern us once the remembrance of our former selves was snapped in twain.3 And we do not now grieve for the selves we once were, though these same seeds have doubtless stood in this very order many times before; between lies a break in life, and every motion has wandered far astray from sense.3
The close of it is plain. For grief or pain to befall a man, he must himself exist at that time for the ill to reach him. Death forestalls this and prevents the being of him on whom such misfortunes might crowd. So there is nothing to fear in death, and he who is no more cannot suffer.3
Death, then, is naught to us, nor does it concern us a whit, inasmuch as the nature of the mind is but a mortal possession.On the Nature of Things, pp. 133–134
the mind cannot exist by itself without the body and the very man... neither without body can the nature of mind by it itself alone produce the motions of life, nor yet bereft of soul can body last on and feel sensation.On the Nature of Things, p. 124
For, if by chance there is to be grief and pain for a man, he must needs himself too exist at that time, that ill may befall him. Since death forestalls this, and prevents the being of him, on whom these misfortunes might crowd, we may know that we have naught to fear in death.On the Nature of Things, pp. 134–135