Life is never particularly long, and for some of us it is especially short. Could it be longer? It seems that it could: our lives are not necessarily of some precise length. Would it be good if it were longer? Assuming life is good, then it seems, at least to most of us, that it would. And so it seems that death is bad, in depriving us of this longer life. The Epicureans, of course, disagree.

Lucretius offers the following argument in support of the Epicurean view. Think of life as a brief flurry of activity, falling between two periods of nonexistence. Life could be longer either by dying later or by being born earlier. If it is bad to die when we do, and not later, then surely it is in the same way bad to be born when we are, and not earlier. Our activity could be extended at either end. But we do not regret our non-existence before we are born. We do not think it is bad that we were not born earlier. So we should not regret our non-existence after we die. We should not think it bad that we do not die later.

The argument appeals, then, to an alleged symmetry between prenatal and post-mortem non-existence, and encourages us, in light of this, to be rid of our asymmetrical attitudes.