Topsoil - this photograph caused me to think about the tenuous grasp we have on life

there is an oft quoted comment on the idea that '6 inches of topsoil sustains all life on our planet' and this view of our thin layer of atmosphere - up to 300 miles  but basically the first four miles is what we are able to breathe and that is 4/8000 (1/2000th) of the diameter of the world - we survive because an extremely unusual quirk of of our planet - no other in the solar system - that sustains us