Now John annexes the reason why living for the lusts of the world is such utter folly: “The world passeth away, and the lust thereof.”  It is the sheerest madness for a man to wholeheartedly dedicate himself to something which will perish in a few short years.  It is the philosophy of the world to dedicate itself to winning trophies which will rust and decay, to glorifying a body which is going to sag, wrinkle, grow ugly, and then die and rot away.  A man should seek to serve his own generation, but not so that his generation will praise him.  Rather, like David, he should “serve his own generation by the will of God.”  The only lasting good we do in this world is the good that we do to the souls of men.  The child of God understands this, and thus he strives to do the will of God.  The man who lives to accomplish God’s will abides forever.  His body may die and decay, but his good works are treasured up before God, and will be rewarded, albeit by way of grace and not of merit.  Contrariwise, the individual who lives to gratify his own lusts or to exalt his own reputation will soon find that his best accomplishments are fading, and will do him no good whatsoever when he sinks into the grave.