Atheists and secular humanists affirm that this life is the only life there is, that there is no afterlife, reincarnation, or survival of a soul beyond death, and that a person's existence is bounded by birth and death. Death is understood as the permanent end of the individual, and hopes and fears of a hereafter are set aside. Rather than diminishing life, humanists hold, this recognition heightens the value of the time one has and directs concern to the well-being of oneself and others in the present world.
The classical statement of this conviction is Epicurus's Letter to Menoeceus, which argues that death is nothing to us, since while we exist death is not present, and when death is present we no longer exist, so that the wise person has no reason to fear it; Epicurus held that most human anxiety and superstition traces to unfounded fears of divine punishment and of conscious suffering after death, and that dispelling those fears through correct understanding of nature is the actual path to a tranquil life, an ancient argument modern secular humanists and atheists frequently cite as an early statement of essentially the same this-life-focused position they hold today. Epicurus's argument survived antiquity chiefly through Lucretius's Latin poem De Rerum Natura, a copy of which the Renaissance scholar Poggio Bracciolini rediscovered in a German monastery in 1417 after it had been effectively lost for centuries, a rediscovery historians credit with carrying Epicurean this-life philosophy back into wide circulation.