" Do you know, Richard, that it's the weight of one flake of snow that is one too many, and causes an avalanche? Without that one, last flake, the catastrophe would not happen. When using magic, you must know which is the one snowflake too many before you add its weight. The avalanche will be out of all proportion to what you think the weight of that flake could invoke. "

― Terry Goodkind , Stone of Tears (Sword of Truth, #2)