It's taken me 60 years, but I had an epiphany recently: Everything, without exception, requires additional energy and order to maintain itself. I knew this in the abstract as the famous second law of thermodynamics, which states that everything is falling apart slowly. This realization is not just the lament of a person getting older. Long ago I learned that even the most inanimate things we know of - stone, iron columns, copper pipes, gravel roads, a piece of paper - won't last very long without attention and fixing and the loan of additional order. Existence, it seems, is chiefly maintenance.