How does Philip K. Dick use the novel to reflect on the themes of what is real and what is human? What are some quotes to support this?

One of
the issues we need to deal with in answering this question is the fact that the blurred line
between humans and androids has been explored so often in sciencethat it could now be regarded a
clich©. Philip Dick nevertheless presents the puzzle of distinguishing between the human and
artificial in an especially striking wayat least as it was at the time his novel was first
published over fifty years ago. Interestingly, as just one similar example in science fiction,
the episode "Requiem for Methuselah" of the original Star Trek
appeared in the same year as Do Androids Dream of Electric Sheep?
This also features a young woman character who is an android without at first knowing
she is.

Most readers are probably struck by the coldness of Deckard as he
begins his investigations at the Rosen company. We have already been told about the complexity
of the Nexus-6 androids, which have "two trillion constituents plus a choice within ten
million possible combinations of cerebral activity." One has to wonder if this might be a
greater degree of sophistication than human beings have.

Still, if being "human" resides in something intangible and separate from the
physical complexity of the brain and body, then what is that quality? Is it empathy? Deckard,
after administering the Voigt-Kampff test to Rachael, peremptorily announces, "You're an
android."

He's correct, but evidently he hasn't considered the
possibility that the Voigt-Kampff test has failed, or (which is actually the case) that Rachael
is an android but doesn't know it. Or perhaps Deckard doesn't care. If an artificial human has
been programmed not to know they're an android, then what, in terms of the
being created this way, is the actual difference between "human" and "not
human"? Both Deckard and Mr. Rosen seem to act in a less human fashion than Rachael does.
Rachael turns pale when she is given what appears to be proof of her being an android.

The artificial being comes across as the most sympathetic character in the story at
this point. Deckard has coldly asked, "Does she know?" Presumably since he's a bounty
hunter, even in normal circumstances one would expect Deckard to be a typically hard-boiled
character, as in "conventional" detective fiction. Dick's combination of that genre
with the science-fiction/dystopia format gives a different slant to the scenario, going back at
least as far as Mary Shelley's Frankenstein, in which we, as readers, are
faced with both the moral and the scientific implications of what being "human"
actually means.