We are going to die, and that makes us the lucky ones.  Most people are
never going to die because they are never going to be born.  The
potential people who could have been here in my place but who will in
fact never see the light of day outnumber the sand grains of Sahara. 
Certainly those unborn ghosts include greater poets than Keats,
scientists greater than Newton.  We know this because the set of
possible people allowed by our DNA so massively outnumbers the set of
actual people.  In the teeth of these stupefying odds it is you and I,
in our ordinariness, that are here.    
                           - Richard Dawkins