• The Stone Age did not end because humans ran out of stones. It ended because it was time for a re-think about how we live.

    William McDonough: The Stone Age did not end because humans ran out of stones. It ended because it was time for a re-think about how we live.
    "Eco-designs on future cities" by Jo Twist, news.bbc.co.uk. July 14, 2005.