"Discovery consists in seeing what everybody has seen and thinking what nobody has thought." What does this quote mean?

This quote means that the essence of true discovery is an
internal one.  A person does not need to be an explorer or conquer the world over in
order to be worth of "discovery."  It simply involves being able to fundamentally see
and think things that others have not been able to formulate.  Think of a chess game
between two people.  They stare at the board for a while and contemplate their next move
in order to be victorious.  They stare and continue to stare until someone from the
outside takes a gander at the game and "sees" a sequence of moves that one player can
take to easily checkmate the other.  The outsider represents this concept of "discovery"
because they "see" what others "see" and "think" what no one, in this case the two
players in our chess game," had been able to think before.  This is where discovery
rests.  The quote suggests that discovery is in the heart and mind of each person, in
the capacity of each individual in order to transform their
world.