Nile River Delta, Mediterranean Sea (NASA, International Space Station, 08/18/11), a photo by NASA's Marshall Space Flight Center on Flickr.
... you cannot understand 'true beauty, true happiness, unless you also understand the depths of despair and sorrow. So do that painful learning down in the silt; because the silt is your delta.'
(delta = fertile place)
From interview with artist John Olsen
The masterly Mr Squiggle, by Janet Hawley, Good Weekend, 2 September 2006.