Blade Runner (Do Androids Dream of Electric Sheep?)

Blade Runner is a movie from 1982, directed by Ridley Scott, that was based on Philip K. Dick's 1968 novel Do Androids Dream of Electric Sheep?  The movie is one of the greatest science fiction films ever made.  The book is very different from the movie; more meditative.  It's a story about a bounty hunter Rick Deckard, and his job of hunting down "replicants," or "genetically modified organisms" that are very close to  human beings, except that they have a lack of empathy and a life span of four years.  In the novel, the Earth of 2019 is a dystopia, a dust covered world decaying into ruin:

     "In addition, no one today had remembered why the war had come about or who, if anyone, had won.  The dust which had contaminated most of the planet's surface had originated in no country and no one, even the wartime enemy, had planned on it.  First, strangely, the owls had died.  At the time it seemed almost funny, the fat, fluffy white birds lying here and there, in yards and on streets; coming out no earlier than twilight as they had while alive the owls escaped notice.  Medieval plagues had manifested themselves in a similar way, in the form of many dead rats.  The plague however had descended from above.
     After the owls, of course, the other birds followed, but by then the mystery had been grasped and understood.  A meager colonization program had been underway before the war but now that the sun had ceased to shine on Earth the colonization entered an entirely new phase.  In connection with this a weapon of war, the synthetic freedom fighter, had been modified; able to function on an alien world the humanoid robot--strictly speaking, an organic android--had become the mobile donkey engine of the colonization program.  Under U.N. law each emigrant automatically received possession of an android subtype of his choice, and, by 2019, the variety of subtypes passed all understanding, in the manner of American automobiles of the 1960s.
     That had been the ultimate incentive of emigration: the android servant as carrot, the radioactive fallout as stick."

The replicants Deckhard hunts have made a violent escape from the Mars colony, where they were property and slaves,  and have assimilated themselves back on Earth.  There are some great questions raised in the novel, and things are very ambiguous:  What does it mean to be human?  Are replicants human? Some humans lack empathy; is Deckhard a replicant?  Is the struggle to raise oneself up out of entropy and decay only a human endeavor?  Is spirituality real?  In a world where everything is artificial:  pets, emotions from a "mood organ," the religion "Mercerism," what is real?  What is reality?  What do replicants read on Mars?  Answer: "Pre-colonial fiction.  Stories written before space travel but about space travel."  They read Science Fiction!  The book is a good read, especially if you are a fan of the movie. 

One of the greatest scenes in film isn't in the book;  Rutger Hauer wrote it (!) and he really nails this scene, here it is: